A lot of factors, the people getting 80-100k in 12 hours or so have 9-12 Salvage Protocols (I run 3 Radar and 9 Salvage) Box Doubler + Tractor Beam II 5/5 and perhaps Luck 1+2. (I personally don't run Luck 1+2 because the difference in Uri is only like 40-60 on the bigger boxes and the spins should be the same).
Also from what I've seen if you bot say 12 hours straight then wait around 6 or so hours, the amount of Uri you get seems to stay the same or go up. I've been botting on a dummy account just to see the rates before I do this on my big ship. When I bot from 7 AM to about 7 PM (or 5am to 5pm it just depends when I feel like setting it up, I always do a 12 hour stretch though) I get about 50k or so (That is with only a Box Doubler and 9 Salvage Protocols, no Tractor Beam) on maps X-2, X-3, and X-4 (The event boxes are 50% higher, so same as the B-Maps plus you get Fuel and other useful things). I then stop until around Midnight then bot from Midnight to about 5 am. I then stop and wait about 6 hours after reset and do it all over again.
I have yet to see any decrease in my Uri or Gate Spin gains (I average with this setup around 70k Uri and about 1k Spins a day, with Tractor Beam II it would be around the 100k Mark and around 1.2-1.3k Spins, with no B-Map botting at all). I've been doing this for about 3 weeks now and my account is untouched as far as all the ban waves go. You can safely bot for like 12-18 hours a day, just don't do 22-24 hours, that is why people get banned, or they never change maps, etc.
This is all done using CandyBot btw, I still find it to be the best pixel bot to use. The others just give me problems no matter how well I set them up. But these results should be about the same no matter which bot you use (Anyone notice that far more bonus boxes appear in 3D mode than in 2D mode?, I think a 3D bot would have massive gains due to that fact).