There's a schism among fitness professionals. In the middle is the model of generalized personal training, such as that proposed by the National Academy of Sports Medicine's "OPT" model, which aims to personalize client programming according to mobilization, stabilization, strength, and power development. This school of thought places a large emphasis on traditional, bodybuilding-style isolation movements that are generally at lighter weight and lower intensities than traditional heavy barbell movements like squats, deadlifts, and presses. There's a growing view that this style of training is not particularly effective, and this view has split into a couple of broadly divergent schools of thought.
At one side of that is a growing chorus of movement and stabilization specialists, who place a heavy emphasis on mobility development and rigorously precise dynamic and static postures. Entire training protocols are developed around the minutiae of muscular activation and control, with the thought that this is the most optimal way to train pain-free and with minimal injury risk.
At the other side of the traditional personal training approach is a sort of throwback—an emphasis on simple, heavy strength training. Some of these individuals essentially dismiss corrective exercise and mobility work as a waste of time. They emphasize the repeated execution of basic movements with progressive resistance, and generally believe that technical errors can generally be corrected with simple practice and mindful coaching rather than incorporating time-consuming correctives.
Diverging from the model
Recently I trained a client in his early 40s who, a few years ago, suffered multiple strokes. We'll call him Dave. Dave has since lost a significant amount of weight primarily through dietary changes, but he had some understandable anxiety about strength training. His lack of motor control and strength on his left side, a remnant of his strokes several years earlier, often left him afraid to even try basic strength-training exercises.
Within three sessions, he was doing low-bar barbell back squats with 65lbs. A very light weight, certainly, but remarkable progress nonetheless. Now, if I were to compare Dave's barbell squat mechanics to those of an elite powerlifter, there would certainly be divergence from the model of what we consider an ideal squat. He has difficulty tracking his knees properly; his depth was a bit inconsistent; he had trouble finding a good bar position.
And yet, his squats were, in my view as a coach, good enough. He didn't demonstrate valgus knees (caving inward) or excess lumber flexion. He was able to maintain his balance on the midfoot and brace properly during each rep. Though many aspects of his squat were not yet ideal, that's okay because he's a total novice. His squat did not look like that of an elite lifter, but he was not lifting anywhere near the intensity of such an athlete. We should not expect that someone who has no experience squatting under load should demonstrate the same measure of consistent technical precision as someone who has been at an elite competitive level for many years.
The question, for a coach, is how much diversion from the ideal we ought allow before integrating corrective exercises. On one extreme are coaches who believe that the movement must be brought as close to the ideal as possible through corrective exercises before any load is introduced or progressed. On the other side are coaches who believe that practice and cues are sufficient to weed out any technical errors over time, and that time spent on corrective exercise would be better spent on mindful practice of the exercises.
What works for some....
I tend to fall somewhere in the middle of these two camps. Personally, I have seen correctives—mobility drills, stabilization cues, and activation exercises—work with remarkable speed and efficacy in many, many clients during my 14 years as a strength coach. To dismiss them outright, as some do, is in my view a shortsighted approach that short changes the client. On the other hand, I've seen coaches all but avoid basic strength training out of fear they will injure their clients if movement patterns aren't virtually flawless.
Muhammad "Sword" Sultan, Egyptian national weightlifting champion, posted some time ago on his Instagram his overhead squat positions before and after he had spent a few months improving his ankle mobility. His mobility prior had been sufficient to propel him to a national weightlifting championship, but it still was not ideal. With practice and mobility work, this elite athlete was able to improve his positions and become that much better a weightlifter. This kind of minor technical correction indicates that ideal positions may be elusive, but also that a certain amount of divergence from the ideal is normal, even among elite athletes.
One of my own clients, a competitive powerlifter, had a persistent elbow injury leading into her last competition. The injury was aggravated by sub-optimal bar position in the squat, but we did not stop squatting—we adapted. We were able to manage the pain and work around the injury leading in, but for her next prep cycle we decided to use specialized barbells to prevent aggravating the injury while she pursues rehabilitation under the guidance of a specialist.
There will be many athletes for whom simple coaching cues and practice will indeed correct a number of mistakes. As the body gets stronger, it seeks efficient movement patterns and, with time, many common novice errors are weeded out simply through mindful repetition. But in many cases, the athlete demonstrates a persistent error that is resistance to correction through cuing. In those cases, it may be wise to integrate corrective exercise.
Loaded vs. Unloaded
In a loaded barbell lift like a squat, deadlift, press, clean & jerk, or snatch, there are fundamental differences in the movement compared to doing the movements without any load at all. The ability to perform an "Asian squat" without load, for example, does not indicate the the individual can stabilize a barbell overhead in a full squat—as in the receiving position of a snatch. This is because in bodyweight movements, the athlete's body is the center of gravity; in loaded movements, the barbell becomes the center of gravity, and the mechanics of the movement must adapt accordingly.
For that reason, preventing athletes from training under progressive load out of fear they will injure themselves simply robs them of the opportunity to adapt. Failing to load at all, or failing to load progressively, are just as fundamentally misguided as increasing the load too quickly or ignoring technical mistakes altogether.
When Dave squatted 65lbs for 3 sets of 5 reps, he made many minor technical errors. Sometimes his knees wobbled a bit and he needed to be reminded to drive them outward as he descended. Sometimes his hips rose too quickly, and he had to be reminded to "push the floor away" through his midfoot. The bar position was a bit asymmetrical due to mobility restrictions and a lack of muscular control on his left side. But none of those issues prevented him from learning how to put weight on a bar and squat. Over time, repetition of the movement will allow him to hit depth consistently without being reminded to push his knees outward. We'll likely have to work on his shoulder mobility through some simple stretches, but he'll also learn to adapt to the proper bar position with practice.
It's also likely that as he progresses, other minor technical errors will crop up. That doesn't mean he should stop squatting; it just means his errors need to be addressed as they come. Sometimes just a slight regression in weight, combined with simple cues; other times, it may be some simple stretches or activation exercises. But what's important is that he keeps training, keeps progressing, and keeps getting stronger.