mumu64, thank you for the kind words :D
The one before a stage is 100% cosmetical and has been drastically shortened since then, because I got sick of it, testing the game so much (or at least wasting a lot of time hoping I'm doing it right!) x) That and the screen wasn't nearly as cool as I thought it would be!
The door ones are intentional. Since the game keeps track of your time, I encourage trying to go fast, making things a bit frantic, so I thought a bit of respite for the player would be needed. Since time doesn't advance during them anyway, I guess I could make it a customisable thing?