It isn't really. Tho it seems brutal for once per 5 levels. It really isn't because even if you die on the first level you can know how to beat it immediately or maybe after a few tries. The thing is if you add a checkpoint right after that it's the same thing as it doesn't really become a challenge at all as every level is the basic trial and error and is quite easy, but if you do multiple checkpoints after maybe 3-5 levels if you want to be more forgiving, then it gives a sort of challenge and makes it more fun. (Damn that's long and btw if you think 5 is too much then do 3 since it still gives challenge)