It did work for me.
when all the slots are full after 40 hours, then after 8 hours (so 48 hours in total) you get the amount of one slot added to your balance.
Yes, you are right.
When you will have 5 slots full and pick up an ore, you will see that timer shows actual time for a new ore and not a full 8 hours, like when an auto clicker is disabled.