The University is only capable of boosting a maximum of 50 RZs at once, despite the fact that you can fit way more RZs in a 22x22 area. The 50 RZs that get boosted are random and change every time you restart the game, move a RZ, upgrade a RZ, etc. If you have RZs in different states of upgrades, the boost may switch from a large tower to a new house, and you'll see a drop in total population. Boosts can also switch from RZs that only have 50% boost to RZs that already have 100% boost (if you have multiple Education boost buildings), making the extra 50% boost pointless.
