IIRC for incandescent it was about 1/3s to break even. For fluorescents it is likely higher but don't have a source (it may not be an issue if the starter is smart enough to realize that it isn't needed or not needed as much). However there is going to be extra wear and tear on these bulbs which makes the savings offset by extra bulb replacement. For LED the cost of turning off should be very near to zero so this would likely actually save resources.

Of course this idea is awful for other reasons. But it is very funny.