Interesting question. I think it depends on (probably a whole bunch of factors but....generally, assuming your limiting factor on your RM is your pressing strength) how conditioned you are and what percentage of your rep-max the heavy, medium and light days actually are. If your light day is a low percentage of your actual RM on that day, then your limiting factor will be probably be your "conditioning" (i.e., you're waiting for your heart rate to recover enough so that you can keep doing subsequent sets without so much glycolysis). On the heavy side, my understanding is that ATP replenishes non-linearly (i.e., the first ~3/4 comes back pretty fast; but the last ~1/4 takes a lot longer); so if you push much past needing ~3/4 of your ATP for each set, your rest periods start having to increase exponentially the further past ~3/4 you go.
So my last 2-weeks of 1.0: Heavy day went from 43 to 54; Medium day went from 57 to 66; and light day went from 68 to 76. So in week 1, "light" was about 60% more than heavy; and in week 2; it was 40% more than heavy. I guess that means my RM went up, all other things being equal (which they probably aren't; how my elbow and callouses felt, how much I slept, how hydrated I was, work stress; etc.)
In theory, at some point (if I just stayed with 1.0 with the same weights), my actual RM would increase enough that these numbers would actually turn around (which is effectively what happened when I did 3.0; but the heavy day is 3x the light day; not 1.5x the light day like it is on 1.0) but at that point, I would not be working with anything close to my 10RM anymore, so I would no longer be doing "the program". I suspect the program progression from 1.0-1.2 is set up to anticipate normal progress most people would make so that the heavy/light range is always in this window. If you just jumped straight in to 1.2 using your ~10RM, I'd think you would spend a LOT of time resting between heavy day sets..... I don't plan on testing it out ? .
If your limiting factor on your RM isn't your pressing strength, but maybe that you "gas out" from the cleans; perhaps the above is completely non-applicable..... (actually, I'm no trainer; and it certainly may be "non-applicable" anyway
).