I think it does:
First time I went to resource extracvtion site today, I had one Anaconda after another and earned something around 660k in around 20 minutes. Site was spawning me one Elite Conda after another with bounties ranging from 50k to 130k. Went to reload my guns and went back after 3 minutes and then only Cobras and Sidewinders spawned with bounties around 2k -30k. So propably site resets when you leave it... Edit: ALso worth mentioning it was a Federation system.
Also I noticed that same thing applies for other places. I was bounty hunting in same system for couple of days and now almost all ships are clean and no big boys hop in (just dinky sidys, vipers, cobras). I am master in combat just from npc bounty hunting so it's based over 8mil credits experience
