https://www.youtube.com/watch?v=uboxvvslIIA Looks like hitting the jump chain requires you to jump 26 frames after the spin input. It feels the same on PC but I can't be certain as I haven't looked into the PC game's tick rate. This could lead to some big skips if someone feels brave enough to hit multiple frame perfect inputs in a row for timesaves. The timing on PS1 can be different by a frame or two depending on lag frames.

Yea it can also bedone on Roman Beavers if you jump from a higher place first. It's just so precise, so it's more about planning ahead on how many risks you want to take with using it in a run. I used some risky double jumps in level runs but doing them in full runs isn't really worth the risk, if failing one results in death. You can get more consistent with practice of course, I think I could land a jump close to 75% of the time but that's still very risky. I also used a playstation controller binded to keyboard inputs which helped me be more consistent.