I'm new to this game and I'm making offline runs of GP any%, and since I'm new I mess up some times (BTB), so before I do that I save and if I make a mistake I load. So is this allowed? and if it's not, it's just better to reset?

I started doing smb speedrun, and I use nestopia because at the moment I can't get nes, one thing I noticed is that in all speedrun videos the pattern is different from mine, in 4-1 I always take 341 seconds and I have to slow down instead of not slowing down, at 8-2 I can’t get past the stairs in one cycle because lakitu always hits me but in the speedrun videos it doesn’t happen, at 8-4 start I always walk on the second step and never in the third, and sometimes if I go too fast I hit the piranha plant in the pipe after the hole with lava and I heard that this is impossible. I already tried on fceux and nestopia in both versions (pal and ntsc) Please can someone help me