Alistar's Trample can't be recast if it's already going

I know this might seem like a stupid thing, but it makes a huge difference in URF.

With the overloaded CDR Trample starts with a 3 second cooldown, but Alistar tramples for 5 seconds. Similarly Tristana's Rapid Fire lasts 7 seconds with a CD of I think 4 seconds. Rammus' Defensive Ball Curl lasts 6 seconds with I think a CD of like 4.5 seconds. Both Rammus' Ball Curl and Tristana's Rapid Fire can be recast when it's already going, just refreshing the duration. Same goes with a ton of other champion's abilities. But Alistar's Trample needs to wait for the 5 second ability to end before being able to recast, even though it would be simple enough to refresh the duration or queue the ability again.

I'm not sure if there are more like this but I wanted it pointed out, made Alistar feel totally useless on URF.