I did all of my wizard quests today, which is something I never do, and on the 15th one I got the normal 20 point token but also a 50 point token. Is that for doing all 15 quests or is it just random?

It is for completing all of the quests :)

It's not for doing all the quests...it's always given on the very last quest whether it be 10th or 15th. I've had a couple cases where I quit one quest but one the 15th (since I have a GA) I still got the 50 pt token

At least that's what I think. I don't really think it's for doing all quests, since as I said above, I got 50 pt tokens even when I quit one quest and did only 14.

Just tried it out, quit 14 quests and completed the last one. 50 point token acquired, you are correct :)

Yes, I've noticed it also. It's a pleasant bonus, I wish other quest givers would have something similar in store.

So it looks like it's for doing all or almost all the quests, does it have anything to do with having a GA?