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.

I am generally against fan fiction so no.

No, I don't. So, the option is ‘Never’.

Never. Fan fiction can rot in hell. Make up your own story!
The legality of it is pretty interning though. Most publishers won´t care about such things, as long as you don´t make money of those, and Japan is even more lax BUT the whole concept isn´t as legal as most think. Quite the opposite actually.

Where would you even find them TLed?

Only one i could ever find was Ichaicha Railgun

The only purpose doujinshi really serves (aside from hentai) is shipping... but there's no option for that.

Seldom. Like someone else mentioned, djs are for shippers, which I am not. I always come across the yaoi djs, where they take straight characters and make them into gay lovers. Now I love yaoi, but I don't like seeing my favorite characters changed. Where I do appreciate djs is when they have characters who are a couple in their original series. I really loved these djs of one shoujo manga I read. Of course with it being shoujo, although the characters finally get together in the end we don't get to see any of the details. Since I love smut, I really liked the djs that depicted that and it felt like an extension of the story rather than some alternate reality.

Now not talking about manga, what really shocked me is that a TV show I love, Supernatural, has a lot of fan fiction and djs where they make the main characters into lovers. Big problem here as the main characters are brothers. Like seriously, people! Who comes up with this BS?

I own a lot of raildex doujinshis. Except for those I don't read doujinshis a lot.

Depends on the series. Most series I don't look for doujinshi. I don't need it for shoujo, josei, or BL. But I am a trash yaoi shipper who cannot be shamed. If a pairing in a shounen manga or anime strikes me, I'll look for the doujinshi, sometimes as soon as after reading just one chapter or watching the first episode. I think of dj as telling the parts of the story that the author left out. The only het pair I have tracked down dj for is Vegeta x Bulma. Good stuff, more interesting to me than Dragonball Z itself, which I find boring.

I put seldom. I don't see the point except for some really good ones like the dragon ball x onepunchman crossover that I recommend, It's quite funny (SFW)