Here I have been paid in the past as a subcontractor, which is close to the same thing as being paid by the project. As a mover I discovered that one can lose as much as one can gain. This is the disadvantage of being paid under contract. The advantage of contract is that you are paid more. Thus it is a trade off that depends upon your ability. Getting a job means you don't have to worry about that, because you are paid for your time and not what you produce.