Ancient Coin AFK Supports
I don't literally mean AFK supports, but supports that take ancient coin need to do VERY LITTLE to get their coin gold compared to other supports who really have to engage in the lane and trade.
Thresh, Pyke and Rakan can just sit around in lane doing nothing and get their supp item completed at 9min by collecting the gold coins.
To make it a more interactive lane item I suggest the following:
If a coin is not picked up, another coin will not spawn for 45 sec.
The only time you miss coins is when you're getting pushed in, and for a coin support lane, you should be pushed in all the time if you don't offer any pressure.
and it's 20% cooldown.