I don't think it's necessary to 100% max. Leaving more than 1 builder idle is very inefficient. I upgraded to TH9 after finishing skulls but still had over a month left for buildings. Which allows me to be able to finish heroes and buildings at the same time if I wanted. However, I'm upgrading a bit early 2 weeks from now because lavas will be done and I want to hit TH10 after exactly 1 year of playing.



It's near impossible to finish everything at exactly the same time with almost no downtime. Only reason I'm still there is because of war attacks.


