Well from what I have seen you can accept them on any job, but accepting certain ones will change other ones rewards. For example, I had 3 leve's for rank 40's that gave me Con marks, on accepting one of them the other 2 changed right after one offered less con marks and the other changed to Pgl marks. So from what I can tell, it only matters on what you pick first and it may only effect other leve's so you can not get to many of one type of mark in one reset.