Leveling after 25 is extremely grindy, not that end game is much different. Rebuilding the same map over and over again is extremely boring and in the long run takes a good chunk of time. I propose adding the option to snapshot starting builds and allowing players to instantly rebuild set ups they have snapshotted in the past. Realistically this would be most valuable on wave one for the initial set up, but you could do incremental snapshots to auto-build between waves. It would cut out a lot of the monotonous and boring parts and get you into the action faster.