How long can a person wear one? The few times I work in office I wear one all day, and don’t find it difficult.
How long can a single N95 be reused? I’d read research indicating the real limiting factor seems to be the quality of the seal, and the straps tend to fail before the mask loses efficacy. Basically, if it seals without air escape, you’re good.
I can't wear the 3M ones I have (with a decent seal) for longer than half an hour without getting lightheaded.
Another option is to look for a respirator with an exhalation valve. You give up a level of source control but any exhortations to "protect others!" is pretty silly when they come from people who aren't wearing anything to protect themselves. The Aura has a vented model (9211+) which I've not tried but have heard excellent things about.
You could also consider a half-face elastomeric respirator. You wouldn't expect it, but I've found the ones made with a quality silicone material (3m 75xx / Honeywell North 7700) to be far more comfortable than disposable N95s. They have far more breathable area, which is a major plus. When adjusted properly, they also do not "dig into your face" the same way disposable respirators do - you can keep the straps surprisingly loose & still maintain a seal. And they have a much lower TCO because the respirator media lasts for a long time. Muffled speech is the biggest problem, but speech diaphragms go a ways towards fixing that.
In general though, as you move up the ladder of protection you end up using tools that are both more effective & more comfortable. Pre-pandemic I had a crawlspace under my house spray foam insulated. A team of three guys crawled around under my house in mid-August while wearing full face respirators. They told me they were actually more comfortable than the old half-mask / goggles combination they used to use.
