I had an idea to throw in the ring as far as Warband Reputations go. In the Warcraft Wiki interview with Morgan Day (https://warcraft.wiki.gg/wiki/Forum:BlizzCon_2023_Q%26A#Interview_notes) it was mentioned that The War Within reputations/renown would be account wide- but prior expansion reputations are still being decided on.
I think the issue with it being fully account wide at all times is that it incentivizes having more alts to farm the rep quicker if every point counts. Obviously this would suck.
So there are 2 options from my perspective. #1) you count which character has amassed the most reputation and give all characters that level, or at the end of each week you snapshot the reputation to the highest character on the account and move all other characters up to that level - doing this would mean that doing weekly quests on multiple characters would not assist, but that a different character could be used week in and week out to gain reputation at the same speed as someone using the same character the whole time.