My answer to op, assuming they're not being facetious:

- We need time to recharge and let our brains work asynchronously on problems.

- We need more coordination and integration points with colleagues. If we're steamrolling ahead, there's little chance to coordinate.

- Quality of work begins to suffer after a certain point and reaches diminishing returns.

- Expending that much effort at once, repeatedly, likely leads to incredible burnout.

- Personally, the will to do Herculean tasks isn't a renewable resource you can tap into week over week. It happens, but it depletes. There have to be breaks.