This is the first time I've ever put the effort into beating it and I've beat it 3 times now and still no exclusive rewards, is this normal?
This weekly seems pretty easy compared to others I've tried but do you have to play 5 or 10+ times to get the exclusive stuff once?
First time of the week is a guaranteed effect (can be crimson or purple), after that it´s just a chance of getting another one. If you finish the quest with a character that has the effect already for everything (idle, execution etc.) you will get the effect for a random character
I don´t know if they changed the drop rates cause I don´t grind that mode anymore but last November I grinded with a buddy for like 3hours and the effect dropped a good 70%