Why does it take long time to update Garmin maps?

[marklee9161 0]

I’m a user of Garmin GPS device and want to update my Garmin GPS devices. I have a huge collection of small and large sized map files. These files have some important information’s.  I’m trying my hard efforts to update Garmin maps, but I am failing to do it. So it has become a huge trouble for me. I need someone’s help for clearing out the concern related to Garmin map update. Can anyone suggest me why does it take long time to update Garmin maps?