I picked "very seldom" instead of "never" only because I've actually read the doujinshi that Naked Ape wrote for Switch
. They were pretty nice, with only vaguely implied pairings, but since typical dj's are either hentai or yaoi/yuri and I'm not a "shipper," that kind of stuff is just gross. Especially if they involve non-canon pairings (which they do more often than not, lol).
I've read quite a few original doujinshi, though, with some of them being more decent than the mangaka's published work; probably because they have more creative freedom without editors and "popular opinion" breathing down their necks
But of course those aren't what the poll question's asking about.