What’s your formula for paying crews per job?

I struggle with this one. I think piece work would be much better for the employee and for the business but for our company it's really hard because we do so many different things. Even things that are somewhat similar are different (like a gate for one person isn't a gate for another). One thing we've done is a hybrid hourly model then use Protiv (which integrates with jobber) to give them a bonus for doing it faster with no all backs. That's still a work in progress though because they are still working out the kinks on their end.