I mean, my family's investment company is far, far from being an institutional investor, but the math is pretty solid. If our plan is to buy Apple and sell it in the next six months if it rises by 15% then it is pretty easy to justify selling the calls with a strike at 15%, which I know isn't perfect because if something substantial changes at Apple (a new product, say) then in the case where the calls weren't sold you could re-evaluate your target, but that type of event doesn't happen too frequently and if we would have put a sell order at 15% above anyway it's a near-free increase in returns. Because inflation eats the first couple percentage points and taxes don't take that into account the delta in gains does stack up over time.
Selling puts, though, is a fools game unless the market has already really tanked. Black Scholes isn't perfect, yadda, yadda.