Momentum is not a sprint, it is a rhythm. The trick is to pick a weekly cadence that your team can sustain without heroics.
I run a small loop: scope on Monday, build midweek, polish by Thursday, and ship or demo on Friday. If we miss the Friday ship, we still demo and close the loop so the next week starts clean.
The result is boring in the best way. Small wins add up, and the system keeps energy high.