A tidbit from the 744 maintenance manual about alignment time vs. latitude;
(g) Ten minutes are required to complete the alignment for any
latitude between 70.2 degrees North latitude and 70.2 degrees
South latitude. This is called a regular alignment.
(h) 17 minutes are required to complete the alignment for any
latitude between 70.2 degrees and 78.2 degrees. Since the IRU
will automatically enter the navigation mode after 10 minutes
if the mode select switch is in the NAV position, a high
latitude alignment requires that the mode select switch be left
in the ALIGN position for 17 minutes before being selected to
the NAV position.