I think there's no rule, it depends on the startup, its market, and the potentials ahead

Imagine you be the first employee in a startup that has the potential to become next Uber?

Or a startup that can't be big enough, which the majority of startups are here, in this zone

You should find even 0.5% of Uber is better? Or 40% of an average startup which finally will have a value between $10-$100 million