They don't have a rate. That's the whole point. A W2 employee has to have a rate, hourly/annual/weekly/etc. They have a salary or rate. A 1099 is the only way you can charge per project instead of per rate. When you determine how much you get paid for the project you yourself pick and start is irrelevant to whether you're independent and 1099. In fact if you include contractors working on your house repairs, you have an estimate and agree on the total well into the project.
paid per project you choose yourself =contractor. salary or rate =employee.
determining how much you get paid has nothing to do with employee or not. in fact, as I keep stating, not knowing how much you get paid literally makes you not an employee.