I have an actual IRL fainting problem, so I have written it like...I think once? Since for me it's like "yeah this is a situation where I'd pass out." and it was for a character who hadn't eaten yet, who was kind of sickly...it just made sense. But I have noticed a lot of authors maybe have never fainted themselves? there's usaully steps to fainting, so long as you aren't knocked on the head or something, it's not like "and then I woke up" nah, you can feel it crawl up your neck, and it's like "oh damn oh damn gotta let the person I'm talking to know I'm gonna pass out and apologize ahead of time." Someone who is a fainter knows when it's time to seek a soft thing to sit on for a bit.