If you don't complete the task, you don't get paid, plain and simple. You get paid for deliverables, not for work. For invoicing, I just bill at the end of ea

If you don't complete the task, you don't get paid, plain and simple. You get paid for deliverables, not for work. For invoicing, I just bill at the end of each job--exceptions occur when the client isn't someone that I would necessarily trust off the bat to do this.