If you'd ever been a glider pilot, you'd know!
I have to disagree with this (albeit on an accademic point) unless you happen to have spoilers installed on your aircraft.
If you'd ever flown a parachute however, then you'd know!
Once you're too low it's over for the selected target, so you either have to be dead on, or give yourself some leeway by aiming a little long. By aiming long and controlling with a slip, you're bracketing your target and if it looks like you're going long, you can slip more (or even S turn), if you're coming in a little short, you can ease off the slipping.
That's what the glider pilots are doing, except they're using spoilers instead of slipping. Under a parachute, you have brakes to vary your glidepath.
Good point about the POH, but by the time you're on approach, that's really just accademic.