I have watched my favourite movie and read my favourite books a lot of times, but I don't do it again right after I finish it, 8 times in a row, I would end up hating it no matter how much I liked it at first, just like that hit song that plays so many times on the radio you can'd stand it anymore after a while.

It's the same thing here. Would I mind running Garuda EX 100 times? Not really, I have already because I love that fight. Would I mind having to run Garuda 20 times for a drop, then having to run it 20 times for another drop, then 20 times for lights, then 20 times for an accessory and another 20 times for some more light, all for the same quest? Hell yeah I do, I wouldn't even start the quest in the first place.