buttman wrote:
What does it mean when a controller says "Cleared for landing full
length", or "cleared for takeoff full length"?

I've never heard this said until I started flying out of this airport
I'm based at now which has a 11,800 ft. runway. Does it mean he wants
me to land further down towards the middle of the runway?

In the past, I've always disregarded the phrase "full length" as quasi-
meaningless "supplemental" information (such as "#2 for landing").
I've made about 20 landings so far here, and 3 of them resulted in a
plane behind me having to do a go-around, so maybe there is something
more to it.

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?

You might do what I have done in similar situations of uncertainty: Just
give the tower controller or manager a phone call and ask them what they
mean or expect of you (or any landing pilot). I've always gotten helpful
and friendly information by talking to them directly via the landline.