Another question that's somewhat related is - should the release rate system be simplified overall, in particular, have less increments - perhaps something like 1 to 5, rather than 1 to 99? Some levels would need tweaking, but it would continue to allow puzzles relating to RR manipulation while reducing how fiddly these can get.
Currently, the system allows setting between RR1 (one lemming every 53 frames) and RR99 (one lemming every 4 frames). Perhaps a setting based on 1 to 5 would allow gaps of 4, 16, 28, 40 and 52. At this level of release rate flexibility (or rather, lack thereof), a level could even set allow or deny for each value. (Rule: Lemming spawns every ((5 - RR) x 12) + 4 frames. Equivalent to (respectively) RR 99, 75, 51, 27, 3.
This could be adapted to provide more or fewer increments, if need be. (Perhaps we want it to be 1 to 9, based on ((9 - RR) x 6) + 4 frames - gaps of 4, 10, 16, 22, 28, 34, 40, 46, 52; or equivalent to RRs 99, 87, 75, 63, 51, 39, 27, 15, 3?)
If nothing else, should it at least be simplified to be 1 to 50, given that currently for any even n, RR n is equivalent to RR n+1, giving only 50 different possible delays between lemmings?