Lots of devices take a really long time to do this. Most devices have internal battery backup that keep the almanac between sessions, at which point it can be r

Lots of devices take a really long time to do this. Most devices have internal battery backup that keep the almanac between sessions, at which point it can be really fast. But the (admittedly somewhat old) watches I've had get a really long time to lock if the almanac is out of date or you have traveled a lot since last it was used. It takes 12.5 minutes for the almanac to get propagated. Not sure how much of the almanac you really need or if you can download multiple at the same time. But from practical experience 12.5 minutes seems about right with the devices I've used.