Will flavors marry in compound butter if given sufficient time to rest?
If you leave the butter uncovered in the fridge, it will eventually pick up the tastes from everything else in the fridge.  This really is why there is a special compartment for it.  The compound butter has to do less work to infuse.

Our chef school teacher said they made their compound butter ~2-days ahead of the event so the flavours would infuse properly.  The piece of butter I tried had no strawberries in it, but it sure smelled and carried the taste of strawberry.

I've even done the lazy-man's compound butter by rolling the butter stick in Thyme and stick it in the fridge.