Thanks for the heads up. The three stats have different boosts in my case. Let's say that strength gives a +19 boost, attack +18 and defence +17. I want to drink the potion when the strength boost is reduced to +2. So, 15 to 15 would work in this case?
EDIT:
So, I tried out 15 to 15, but I think it drinks 3 times? Is this possible?