So this was a smaller change I made a while back that I just remembered. Pretty simple, it keeps a timer for each mapslot. When a map is played, its timer gets set to the value of the configured cvar. When maps are selected for possible votes, any map that has a timer over 0 is skipped, effectively removing recently played maps from the voting pool. When a map is chosen and loaded, all timers are decremented by 1.
This ensures maps you have just played don't pop back up for voting until this configurable cooldown has passed.
This particular feature is well tested on my own dedicated servers.