should I do an any percent run but always crouching

No

?

If you want to torture yourself, go for it. I was thinking of doing it for NSMB2, but decided against it for now.

I almost did this but I need a way to open doors while crouching does anyone has any ideas

I dont think that one works chief

You could perhaps do this:
Crouchless%
You must hold down at almost all times, with a few notable exceptions:
1. To open doors or any situation in a level that requires the use of the other buttons
2. On the world map
3. After you complete a level

What about pipes you need to press up for like in 5-2

I've tried a crouch only run before; you need to uncrouch for all pipes. There are a lot of reasons why the crouch-only run is bad and arbitrary. You can do it if you want to though.

Actually their is a glitch if I throw a shell you can go into the pipes. And on 3ds you can open doors .you just gotta go fast

And if u be mini mushroom u can go in all piles apart from up pipes

Have you been watching Ceave Gaming and Nicobbq?

Yeah

Just ceave