Thanks! Yeah the idea was that when the enemies change the map it takes a while so turrets could shoot them more while they're doing it but I agree it can be a bit slow when a lone enemy is doing it. I'm not sure how I can improve that without removing the feature though.
For what it's worth, in the settings there is an option ('simulation speed') to speed up the game so the waves are over faster. It's also possible to place blueprints while the wave is in progress so you can plan ahead instead of having to wait.