The original question is on a forum entitled "744 Forum" and so appears to relate to the B747-400.
That being the case, starting with the digital Boeings, in common with all the digital Boeings from B737 upwards, there is only one compass installed in the aircraft - the standby compass. With twin FMCS's supplied with heading information from triple IRUs, backed up with Rho-Rho updating from DMEs and/or GPS, magnetic compasses have joined the Dodo as far as commercial airliners are concerned.
The AMM accuracy requirement for standby compasses is +/-5° and a correction card is issued when a new compass is installed. After that a compass swing is a bit superfluous as any pilot who does his scan properly will immediately notice any error and report it. My last three companies have deleted the routine compass swing from the schedule with the regulator's blessing: the AMM Compass swing procedure is only used when installing a replacement compass and the "annual" swing is a simple check airswing, conducted during normal operational flight.
Having said that, other less well equipped or older obsolescent types still use magnetic compass systems and in that case they require annual check swings, compass adjustment and the issue of a correction card. Usually, the check swing procedure requires the aircraft to be in a normal flight condition - for example: engines running, busses powered and services such as windscreen heating, navigation lights, landing lights or other equipment that can affect the compass flux detectors must be switched on. These requirements differ between aircraft types so an exhaustive list isn't possible. Thus, it may be necessary to produce either more than one card, or else a composite card to account for different configurations (e.g. night and day). High power transmissions on HF are intermittent so, although they may affect the compass reading, this is temporary and isn't usually included in correction tables.