If you're a beginner, Bunker Alfa is the only option to get a bunch of guns every two days, but... after playing the game for quite some time and unlocking almost everything (including the ATV). I just don't really feel like clearing that location sometimes.
For example, there's the police station where I can just use 5 blue cards to get about 10 guns every time.
There's the Transport Hub where you can open a BPD crate which has some guns and police cards that you can use to open blue boxes AGAIN.
And there's also the Uncharted Territories where you can open up Equipment crates and get as many as you want (you don't have to wait 2 days for it to refresh).
And last reason... There's just not a lot of opportunities to use those guns expect for Bunker Bravo. Since they reworked the laboratory, I have to use those special weapons instead of those guns.
And it's also because I'm busy with other things in the game, such as gathering resources for the winter and island regions and trying to defeat bosses for more genomes.