A small communication breakdown is enough for everyone to be working on slightly different things. And then you loose focus.
A winning team feels good and keeps winning. A team that hasn't won in a while gets demotivated and keeps losing.
Share results (financial and key metrics) with the company every month.
Experience matters for some roles and not others.
In YC experience, 2 or 3 co-founders seems to be about perfect.
To get the very best people- they have a lot of great options, and so it can easily take a year to recruit someone.