There's no mention that I can find of "landing long" ("landing deep" is sometimes used outside the US) in the FAA's P/CG , AIM or ATC procedures .
So it's fairly safe to say that it's an unofficial instruction (assuming I didn't miss it somewhere).
The main reason for doing it is to avoid a long taxi after landing, but I suppose there could be other reasons too, like coming in too high on a long runway or avoiding wake turbulence.
The point of requesting it - and not just doing it - is that it may mess up sequencing at a busy airport because you take more time to clear the runway, with the result that the tower has to instruct the aircraft following you to go around.
As my first instructor said, "once you're cleared to land
it's your runway".
I've never been asked by ATC to do it
but I have been asked by the tower to "land short", to minimize my time on the runway and let an airline flight take off ASAP.
However, it was clearly phrased as an informal request, not an instruction; something like this: N12345
Clear to land 36L, appreciate a short landing if you can manage it
So I think the conclusion is that landing "short" or "long" is simply an informal way for pilots and ATC to make things work a bit more smoothly.
aviation.stackexchange.com/users/62/Pondlife
When you are cleared to land, you own the entire runway until you exit.
Use it all if you must.
(One exception to this is at Oshkosh, during the annual AirVenture when as many as three airplanes are cleared to land on the same runway at the same time:
one short, one medium, and one long as demarcated by colored dots.)
Having said that, at a busy airport you are expected to land reasonably close to the arrival end, and to exit the runway promptly.
This is an important component of keeping traffic moving smoothly at a busy airport, so if you want to land long you should inform the tower of your request.
A good reason to land long:
If the controller has positioned you too close behind a large airliner so that wake turbulence is an issue, tell the controller that you want to land long.
Wingtip vortices stop as soon as the aircraft lands, and you want your touchdown point beyond the large airliner's touchdown point.
aviation.stackexchange.com/users/291/Skip Miller
I don't think it is documented anywhere that you must inform the controller if you want to land long.
But you should state your intentions clearly as a courtesy to the controller and by effect other aircraft that you share the airport with.
The controller will expect a small aircraft to take the first runway exit.
They plan the arrival stream accordingly.
From experience they know it will take a Cessna 150, for example, 40 seconds between overflying the threshold and vacating at the first exit.
Thus they can space the next aircraft appropriately so that they can give a landing clearance in time after you vacate.
When you unexpectedly fly all the way to the second half of the runway before landing it will take much longer between overflying the threshold and vacating the runway.
This will make the margins for giving the landing clearance to the aircraft behind you much smaller and may even force the controller to order the big jet on your tail to go around.
For screwing up somebody else's plan and causing others to go-around you get shouted at sometimes.
aviation.stackexchange.com/users/19/DeltaLima
Long landings are requested mostly by GA pilots (although airlines can do it too) on longer runways.
ATC is informed about it.
If the aircraft is parked near the end of the runway, or needs to get there, long landing is used as it is faster to fly at 80 knots than to taxi at a much lower speed.
I'm not sure why ATC didn't like it in your particular situation.
It could be that they were expecting you to get off the runway sooner, which you didn't.
This PDF explains this.
I couldn't find any regulations related to it.
aviation.stackexchange.com/users/65/Farhan
ATC doesn't like unannounced long landings because unless they are informed of what you're doing, they will be concerned that you're just too fast or too high and might run off the end of the runway.
aviation.stackexchange.com/users/3504/rbp
In EASA land, you can also be asked to make a long landing because the controller will want to clear another aircraft to land behind you, although you are still occupying the runway.
This tool is called Reduced Runway Separation and requires the preceding aircraft to be beyond a certain distance measured from the runway threshold, before the subsequent approaching aircraft can be cleared to land.
Related question:
When is an aircraft cleared to land?
aviation.stackexchange.com/users/572/SentryRaven
I fly in/out of a small international airport occasionally, the runways are quite long. It is not unusual to land half-way or even three-quarters down the runway.  When doing this, pilots request long landings from ATC. I once did not request a long landing and did anyway and got chewed out a bit from ATC.   My question is:  Is it mandatory to request a long landing or is it more of a courtesy? Where is this information documentated?
Why should I request a long landing?
aviation.stackexchange.com
<faa-regulations><air-traffic-control>
aviation.stackexchange.com/questions/14360
aviation.stackexchange.com/users/553/fbynite
It does not seem to be a requirement to request a long landing. However, there aare a number of reasons for doing so to help the air traffic controller organise other planes. The main reason for landing long is to avoid a long taxi after landing.  Long landing is  usually performed on long runways so that aircraft do not have to taxi for a long time after landing. Although it is not a documented requirement, you should nevertheless request a long landing, as it may affect other aircraft coming in to land behind you.
Requesting a long landing is not a documented requirement. Long landing is requested on long runways so that aircraft do not have to taxi for a long time after landing. The reason a long landing should be requested first is that it may affect other aircraft coming in to land.