Back when I was trying to get a decent time at "Beat 5-4" I noticed that at the double platforms the second one kept despawning when I tried to "speedrun" through them, so I had to slow down and execute that section like a casual playthrough.

In the video above I finish 5-2 in 3 different times to change things a little bit at 5-3, and the second platform despawned in 2/3 tries even thought I didn't change much in my playstyle and didn't slow down at all. I saw Kosmic's video on 5-3 but he just showed ways to dodge specific Bill patterns and probably didn't even notice this event. Does anyone know if something affects the timing that the platforms are going to spawn?

Stomping the goomba will allow the platform to spawn every time. If you have fire, don't shoot it, stomp it. The issue is a sprite overload, so that's why it's important to take out the goomba.

@roopert83 I just tried it, you're totally right. Thanks a lot