Originally Posted by
Bruce Ware
I'd hold off on going to light squat days just yet. Prime Directive: Make the smallest change possible and test the effects before making another change.
2 max weight sets followed by 1 back-off set could be fine; try it and check your performance/recovery. You'll still be adding weight to the bar for the max weight set(s) each session, and I suspect you'll find that doing 2-heavy/1-backoff can take you another couple of weeks on linear progression. At that point, missing reps on the heavies would trigger a minor change to 1-heavy/2-back-off.
The idea of changing out a normal squat day for a light squat day is, as suggested by Sullivan & Baker, an indication of insufficient recovery between training days. The signals for that typically look like "running out of gas" and not able to complete the last reps of the session. Your signal of missing reps at the end of the set is a different indicator.
Then again, I'm a late-stage novice/early-intermediate at this point in my progression, and seeing what has been working for me. At 61, I think I'm doing very well, and I am definitely taking advantage of the information in the 3 SS books.