Good startups usually take 10 years.
In YC experience, 2 or 3 co-founders seems to be about perfect.
The startups that do well are the ones that are working all the time.
... you can think about that for everyone you hire: will I bet the future of this company on this single hire? And that's a tough bar.
Before 20 or 25 employees, most companies are structured with everyone reporting to the founder. It's totally flat.
The most important thing is that there is clear reporting structure and everyone knows what it is.