Personally I think the faster, the better if the goal is to make the game more fluid to stay interesting. If you wait a week, I can see it spiking player count for that first day or two, but then they die out as players figure out “that week’s meta” and settle into another repetitive cycle. But doing it faster (every one to three days) with bi-weekly or so balance patches means that the current combination of “meta heroes” is almost constantly changing to the point where we don’t even know who the best is any more, much like the “old Overwatch” that we all enjoyed. Just how I view it, at least.
I can understand not doing it per-match though as that’d just encourage leavers to dodge until they get to play their main.