We are a federal contractor and have been for decades. The PPA is fundamentally flawed and plays little significance on being paid timely on federal projects. The reason being is that the invoice submission is a multi-step process, that can be delayed endlessly by the FEAD without recourse. The first step in billing on construction projects is to discuss the proposed progressive payment with your FEAD ET. Upon reaching an agreement, you then submit a written CPS for his signature. It is at this point that the government is not held to any time limitation, and we have had ET's hold our CPS's for weeks without signing. We cannot enter our invoice into WAF until this document is signed, and the PPA does not come into affect until the invoice is entered into WAF. So as stated, the PPA does nothing to ensure prompt payment to the contractor if you are dealing with an incompetent or malicious ET.
If payment is ever not forthcoming, you have Miller Act rights.