It depends where you sail. In Melbourne where we sail in sparkling blue water, accompanied by dolphins and a 15 knot breeze, our windward leg can be 1.5km long. You need to cleat the main on the beat, as you are not constantly playing the main. Also it means you can adjust the kicking strap and cunningham easily, or eat a banana whilst still racing
In my previous life, sailing in murky brown water, and light winds on the River Thames near London, accompanied by unspeakable debris ,I wouldd never dream of cleating the main.
The cleats go into a backing pad and you need screws about 30mm long.