If a speed below 35-39 or so is used, then frames are skipped semi randomly.
While this also happens with some browsers and software, in others it does not. For example Window’s photo viewer will view gifs with fast speeds without skipping.
That said, in game engines the programmer has the ability to ensure that frames are not skipped, allowing you to show an image for 1 frame, 2 frames, etc. However because Aseprite skips frames a bit randomly, it is a bit difficult to test fast frame timings for games.