Hi!
100-150 hours?! You machines! There are 168 hours in a week, haven't you slept?!
Regarding mistakes, I can give you some advice:
Make the easy games, but do them well. You can even clone mobile/browser casual games (but add your own mechanics). Many, like me, get carried away by ambition.
Don't work yourself to the bone. It's for your own health. And besides, breaks increase your productivity.
Using task managers is a waste of time. Just have a clear plan (which is already automatic for game clones).
YOU DON'T NEED TO WAIT FOR ASSETS. Your team should have assigned responsibilities. One artist, one programmer, one sound engineer. THAT'S IT. If you have three programmers, then yes, it's chaos. And most importantly, MAKE A PROTOTYPE WITHOUT GRAPHICS FIRST! Because you'll slow yourself down. Making gray cubes isn't scary, it's effective.
Go for it!
The way to create games is to learn from your mistakes. Good luck in the future projects!