Note the conditions: in full and _on time._ It seems the implication here is that the contractor has a rather severe and enforceable penalty for not receiving

Note the conditions: in full and _on time._ It seems the implication here is that the contractor has a rather severe and enforceable penalty for not receiving payment on time, which also makes it easier to collect a late fee. You may not always choose to exercise this option, but having it in your back pocket can deter some sketchy behavior on a client's part. If you don't have it in writing, the case or settlement may take longer to resolve, which means you'll have to cough up more in lawyer's fees, which means the client may be more willing to bet you won't pursue legal action.