Hard question. I imagine but do not know, that the Wars of the Roses saw the end of any public spending on communal defence, other than Henry VIII on coastal defences and the 'Device Forts'. Beyond that I would be surprised if any community was maintaining its walls much after 1500. Even new 'bling castles' were being built in bare brick before 1500 by 'new money' families; they definitely weren't rendered.
Chester's walls were apparently in a very poor state in 1642, with many buildings built against them, inside and out. Fortifying it meant clearing the ones outside and throwing up earth buttresses, ditches and artillery platforms in their place. That said, the stone half-Roman walls still had to be breached before surrender was entertained by the garrison.