Have you ever used an n95 mask? They have a rubber band but that's it. I've always gotten stuff inside my mask any time I've used it for painting or carpentry.

Quite often, at least back when they were available for industrial use. I prefer to use non-disposable p100 masks with a silicone seal. The seal leaves a red mark on your face after a few hours but it’s worth it to not inspirate hazardous materials if your mask gets bumped.

That said, N95 masks can work fine if you fit them properly, which may involve shaving any facial hair outside of a mustache, shortening the rubber straps, or adjusting the metal nose bracket.

It’s worth noting that an n95 mask doesn’t really provide vapor protection so it may not do too much for you while you’re painting but if you’re getting wood dust inside then your mask was either improperly fitted or it’s the wrong size for your face.

No they can't.

Do you mean that n95 masks can't work fine? If so, I'm genuinely curious as to how they failed for you.

I've used them while working on-site at a coal mine, as long as you're using a genuine high quality n95 mask and have it properly fitted you can absolutely wear one for 4+ hours without the inside getting contaminated. It's certainly not fun but I've done it many times without issues.

Note that facial hair can prevent that.