

In 3 days the event will be over, so you'll just have to wait and download everything at once or suck it up and download before you play. They have made changes so it goes a little faster than it once did, but they can't really change the update system without basically rewriting it, which would take a lot of time that could go into new weapons, new heists, etc. It's just a product of what they were working with when originally developing the game.

Basically, it has to unpack the game files, install the update, and repack them after downloading, which requires a lot of free space and takes a while. Why so long? Well that's just because of the way the game updates. Usually it's one update + one hotfix per month at most. Why every day? Well, it's an event and the whole point is that they're giving us free stuff for 10 days.
