What are the most common mistakes you see founders make?

Building getinboxzero.com and sharemint.xyz.

I also run a YouTube channel, "Learn from Open Source": youtube.com/elie2222 

Not having a co-founder and allowing them to do their thing while you do your.

Am not saying one can’t work, but as I get older I think probability of success is higher with multiple. A friend that sold his company two years ago says there should always be three: tech lead, non-tech ops lead, sales lead.

I take it this is two?

That if you have a cofounder you should allow them to do their thing or not?