If you count as +/- then....
Working day shift is +/- 8h half a day is +/- 4h.
In +/- 4h should spawn +/- 48 mobs if you kill them +/- 1shot. But if you are +/- 1 rr you need +/- 10 min to kill 1 mob.
So we recalculate in +/- 4h you kill +/- 24 mobs with condition if no one kill youso if you got killed +/- 10 times in +/- 4h and you need +/- 10 min to go back on spot its +/- 12 mobs killed.
And at the and we have +/- 12x75 = +/- 900
So question is +/- WTF?