1) Compounding. Assuming sustained productivity (this is usually unreasonable), it's not just you outputting 2x, it's a bunch of people cranking out 2x and your next up efforts compound on top of those initial boosted efforts.
2) Timing. Some startups are in positions where launching ~months before a competitor could tip the scales.
3) Hiring. It's very difficult to grow headcount at the exactly correct rate alongside business growth.
4) Fundraising. Growth rate is the top metric for raising additional funding.
Knowing that it makes sense to front-load tour day and spend the rest doing less intensive tasks: answering emails, updating documentation, etc.
It's how far you go, not how fast you go.
The Cocodona 250[1] starts in less than two weeks, but with the Crooks Fire it's looking like C250 will be 200 < C < 250.