"And for the hypothetical guy who can squat 225, the jumps are smaller in absolute and easier to make."
Not to start on a negative note, but that's false. The jumps are smaller, yes, but on a percentage basis it is equal. Just because the absolute weight is heavier, does not mean that the jumps are any easier to make.
+1% jumps from week to week are fairly uncommon. Usually it's a +5% change from week to week.
85% @ 5x5 is going to be difficult if not impossible based on a genuine 1RM.
No matter how long you spend in the gym, your body should be so fried. You probably will still walk the next day, but a number of those reps are going to be 'fight' reps where you are gutting it out. You are completing the work, but the quality of the work degrades heavily. At 80%+ we have to make sure that technique is paramount. If the 5x5 becomes a 3x5 because the 4th and 5th reps are garbage, that is FAR better than hail mary reps. On a 1RM or 3RM there's a bit of a gray area, but everyday work needs to be maintained with quality. Otherwise we're cheating our body and potentially recruiting the wrong muscles. Subtracting a rep or two may mean less work, but it limits the potential of having to take days off because of soreness, or worse, injury.
I have not found a lot who succeed on forced PR programs, where the progression eventually hits 100%+ during the cycle. Most humans perform much getting to 95 or 97%, deloading for a week, and then attempting a PR.
Ideally squats and heavy pulls should be isolated as well. A true heavy deadlift (i.e. 1RM) takes two weeks or more for your body to fully recover from - especially your CNS. If we're in the ~90% range, then we are really damaging our potential. It takes ~72hrs for your spinal erectors to recover from heavy pulls, and putting them next to squats is going to limit your ability to maintain posture. I would suggest moving them to alternating days (i.e. squat for weight on day 1; squat for reps on day 3 & deadlift).
Have you thought about front squats in addition to back squats? It's a good way to really force the body to work posture, as well as strength. How are your deadlifts programmed? Stiff legged, sumo, or clean pulled? Also varying presses (wide and normal grip) is another good way to add variation while growing strength.