The time gold reward wouldn't need any fiddling by DMs - that's the point.
But it would, because over the course of most adventures players do not receive wealth in a straight line based on experience gained in the adventure. It varies.
Over the course of level 1 a party of 5 would expect to gain a level 5 item a level 4 item a level 3 item a level 2 item an enough gold and other treasure to but a level 1 item. But that is only 4 items and gold is usually split. So now you run an adventure that takes players from level 1 to level 2.
One player has a level 5 item, one player has a level 2 item, one player has a level 3 item, one player has a level 2 item and each player have 1/5th a lvl 1 item in gold.
If each one receives a set amount of gold for their time experience then most of the group is left in the cold compared to the rest. The 5,4,3,2,gold distribution works just fine when its for a single campaign, since a single campaign typically has a DM work the same characters over the course of the adventure. But in a persistent world that does not work. When handing out treasure, instead of simply thinking about what his players might need or want, he would have to also figure their current item wealth.
This is compounded as those players enter the next DMs adventure and each have advanced some time between those two games. E.G. lets say they gain a full level from 2 to 3 in the interim.
Now the wealth levels are as above but each one has the "average difference" in wealth between a level 2 and level 3 character. The characters who got weaker items or gold are simply screwed.
This is why i say that it might be easier to simply have players choose their items[or gold] and have the DM's give out "parcels" and players would choose which n+ item they would be getting each level. If you don't gain an item or cash before the end of a level gained by time you simply choose when you level up. Character judges at each level up can verify proper item level[players would have to keep a strict accounting of wealth in this instance however to ensure that no one cheats. In each 5 level span you would choose one of each category, either an item or cash with final accounting happening every 5 levels]
E.G. Bobby the human fighter progresses from level 1 to 5
At level 2 he has not received an item from a DM yet and so choose an item at lvl +1[a lvl 2 item]. He plays in the next game and levels to 4, but the DM awards him 2 parcels, he choses a lvl+4 and a lvl+3 item[two lvl 6 items], he then levels to 5 without getting another parcel and must choose cash or items equal to a level + 0 item[lvl 4 item worth of cash]
This has downsides in that players may be less likely to share their wealth, and low level consumables may be important to survivability, but it certainly solves the major issues of item wealth disparity, and removes the difficulty of choosing items for players from DM's.[unless Dm's don't choose items for players at the moment and i am wrong in that assumption]
