... and it doesn't work out as well in practice as it sounds in theory. I have a #1 lightweight genoa on a continuous line furler (CLF). The reason not to leave up the light air sail on a CLF is that it can start to unwind at the top in a high wind. Once the winds get up into the twenties or thirties (or higher) there is no way to re-furl an unwinding sail on a CLF. The CLF just doesn't give enough control, so you have two choices: Either drop the whole deal and stow it, or bear off downwind to reduce apparent wind and blanket it with the main while you unfurl then re-furl, but if the winds are really high at that point it's wise to drop it anyway. If you're anchored or don't have the main up you have only one option... drop and stow it.

The other issue is when beating to windward in a chop. Even if it doesn't unwind, it's a lot of weight and windage aloft (and foreward) that can start whipping around and start "pumping" the rig. Better to stow it or tie it on deck in a sausage bag.

This is my #1 genny deployed.