completing EVERY SHRINE and getting EVERY TOWER. also defeating all the minibosses eg. hinox, talus.

And getting every photo. Very important.

I'd say that I'm not a completionist.

It really depends on the game for me. If it doesn't seem like the reward would be worth it or if it becomes a chore to work for it; I wont go for it. I really struggle with long games as they tend to have lots of cool stuff off the beaten path. God help me if there's a laundry list of things for me to do in an area. Sometimes I won't want to leave an area due to having one of two things left to find. If I get hung on it enough, it'll hinder my progress and I'll get bored of the game. Which leads to a long break from it.

I struggle a lot with longer games, especially RPG's because I naturally want to do EVERYTHING. I hate leaving side quests unfinished, I had to force myself to ignore them in Skyrim just so I could actually finish the game.

I don't think I'd ever be able to finish Skyrim

No I've only 100 percented Super Metroid and all of the Wario Land games.