I was having a discussion the other morning with a lifter about his footwork in the snatch. He was having trouble adjusting his feet out when transitioning from his pull to his catch. He said something to the effect of "When it's light I don't feel the need to move them out, because it's light enough to muscle through."
True, you can get away with falling out of position or failing to hit positions with light weight because you can still save it.
But here's the thing: you will get countless more reps with light weight than you will with heavy weight. So make those reps count. Drill positions with empty bars, pvc pipes, wooden dowels, and light weight until they are second nature. Your 1rm should look no different than an empty bar, save for whats on the end of the bar. The analogy I used was this
"Think about when you brush your teeth. You probably haven't consciously thought about brushing them for most of your life" You probably apply the same amount of pressure to the tube to get the paste out, use the same hand to brush, and brush the exact same way every single day. Some days you may even do other things like let the dog out or get dressed, all while brushing your teeth, because you've done it so many times that you don't need to think about it anymore. This is how often you need to drill the fundamentals of weightlifting. 10,000 hours."
Here's my general Snatch Warmup. I tend to use some variation of this for all the weightlifting classes I teach.
-Snatch Grip Bend and Reach
-Banded Shoulder Dislocates
-Banded Shoulder Abduction
-Behind the Neck Presses
-Snatch Grip Sots Press
-Muscle Snatch from Knees
-Power Snatch from Power Position + OHS (3+1)
-Power Snatch from Mid-Thigh + OHS (3+1)
-Superman Lat Activation
-Power Snatch from Knees + OHS (3+1)