The reset shouldn't need to be done again unless you change the air filter, an engine sensor, plugs, or adjust the valves. Things do change a little with age, so it might need it again later on. I did mine when it was 2 months old and that was 2 yrs. & 3 months ago and still idles fine.
This is from the dealer setup instructions for a 05 bike:
19. Initialize the ECM.
The GL 1800 uses an electronically controlled
IAC (Intake Air Control Valve) to minimize
idle fluctuations normally caused by air
temperature and load variations.
Idle Speed: 700 ± 50 rpm
In order for the IAC to operate properly,
the ECM (Engine Control Module) must
be initialized.
Start the engine and let it warm up to normal
operating temperature.
Once normal temperature is achieved, allow
the engine to idle, without touching the
throttle, for at least 90 seconds. If the throttle
is operated during this time, the ECU will not
initialize properly and the process will need to
be repeated. Idle speed should stabilize at
700 ± 50 rpm.
