In the time it takes to farm for a possible mirror...you would of gotten animus done....for most people ..some have great luck.
time for math purposes rough times. 10 minutes per levi including form times id say is a decent average. so 6 levis an hour. In 15 hours which is average to get all atmas... youd get 75 levis done. Would be lucky to see a mirror in that time. So now lets x8 and assume static so 600 hours of actual levi time...with the assumption its all clears.

So another number...7hours per book...need 9. 63 hours but round up to 65. and another 10 for doing the books. So now 90 hours for your i100 which willl soon go to i110...lol at mirror farming.

Total playtime for 8 mirrors 4800 man hours.
Total playtime for 8 i100 animus 720 man hours...

math is your friend guys.