I sometimes do this as a form of profit taking on (longer exp) calls, sell shorter term high iv calls as a form of buy write (not purely naked)
i knew a guy who does this daily, park his quarter mill cash in bills and sell spx/spx calls, 2% above the open price.
2% seems like a good number, I once tested for optimal buy write percentage which - for spy - was around 1.5% above closing price (weekly calls). Better to adjust the percentage based on expectations/drawdown market, but ofcourse difficult to achieve