I haven't tested it extensively (after all, there is only so much one can do in 4 days), but I feel like at most mistakes on the previous floor can screw up your run to force you to spam undo. I tried to not go too ham with the difficulty and push it more into the optimization potential, especially in the second half of the tower which is far more open ended.
Thinking back, I should probably have thought about telling players ingame that the undo queue has no limit - you can even undo from the end back to the beginning, so any mistake can be fixed. Granted, it would be more cool to provide also a ton of saveslots, but good luck figuring out how to implement saves during a jam without compromising the extremely important for this type of game level design.