buttman wrote:

But then again, why would it even matter. I'm I'm still on the runway,
the controller can't clear anyone else for takeoff anyways until I
turn off the taxiway... Can someone shed some light on this?


I've never heard it on landing, but on takeoff it's used when the
taxiway doesn't go all the way to the threshold so full length lets
you back taxi down to get the "full length."

The term I hear on landing is "roll to the end." This means you
can continue straight ahead on the runway (usually at a higher
rate of speed) rather than slowing down and turning off at the
first practicable taxiway.