Your lifting improves (or worsens) with every single rep you do. The mindset that every lift during a lifting session needs to be heavy to sustain improvement is dead wrong. I see it all too often in the gym with way too many athletes. Instead of practicing with weight they can lift with proper technique, they increase to weight they can handle - no matter what it looks like. Handling weight isn't the same as lifting with proper form. Then, once they start getting close to their current PRs, they start missing lifts repeatedly because of technique errors.
At the CrossFit Olympic Lifting seminar, you spend about 95% of your time with a PVC and it's grueling. At Outlaw's camp, everyone drilled with an empty bar or just 65# all day.
Working with lighter weights instills muscle memory that's necessary to complete heavier lifts. In gymnastics, I would do literally hundreds of backhandsprings on a line on the floor, then the floor beam, then the higher beam with a spotter, then alone on the high beam. You never ever, no matter how good you were, walked into the gym and started flipping on the high beam without drilling first.
When you work with lighter weights, always go through all the proper positions. Most athletes half-ass reps when they're light, using pure strength or speed instead of technique. During workouts with "cake weight," I see all kinds of "personal technique." Congratulations, you finished 25 cleans in a minute...with a rounded back every time or by throwing the bar way out in front of you. Guess what your body will want to do next time we max your clean and guess why you'll miss that clean....
Your lightest lift should look just like your heaviest lift in technique. Your face may have a bit more of a grimace in the bottom of your max snatch and you may sport a bigger smile after you stand the lift up, but a snatch is a snatch is a snatch - PVC or 185#.
And, by the way, when it says "max for the day" on the board, that means you're lifting as heavy as you can while executing the proper technique you're working on that day. It doesn't mean throw all of your drilling out the window and get that bar up any way possible.
Example: When we are doing a complex with pauses, if your last set is so heavy you can't hold the pause, "but I still did it" shouldn't be your accomplishment. You should stay or back off to a weight you can perform well for that day's technique work. It should be "I did that weight correctly [once or repeatedly], I can go heavier when we do a complex without pausing next time."