In my experience, you start to build long-term tolerance (or permatolerance) if you start taking dissos more frequently than once every two weeks.
What I mean by "long-term tolerance" is the following :
Scenario 1:
Day 1: you take 60mg of ket and feel some effects
Day 14: you take 60mg of ket and feel the same effects, because you don't have any short-term tolerance anymore
Scenario 2:
Day 1 : you take 60mg of ket and feel some effects
Day 3 : you take 60mg of ket and feel less effects, this is short-term tolerance (you would need let's say 100mg to feel the same effects as on day 1, these figures being totally fictive)
Day 17 (3+14) : you take 60mg of ket, but you still feel less effects than on day 1, and no matter how long you wait without taking any disso, you'll end needing a bit more (like 65mg) to achieve the same effects : this is long-term tolerance
So anytime you take dissos while you still have short-term tolerance, this adds up to your long-term tolerance, which almost never goes back to zero ; so I would not advise to take dissos more often than once every two weeks.