when to replace Liberty mouth cushion?

For those who use the Liberty Mask, what is the average amount of time the mouth cushion lasts before you have to replace it? I am trying to figure out if the cushion needs to be replaced, or if the pressure used is making the leak rate higher than it should be.

thank you

I noticed that the Liberty cushions have approximately the same consistency as the Micro.
I, personally had to suffer through the last week of the month with a wonky cushion on my mirage micro.
Of course, I hadn't yet learned how to properly clean the silicone.
Now I use unscented baby wipes only--forget the sink, tap water, and any dang unscented soap you can find!
It just wrecks the cushion.

When I start getting leaks that tweaking straps won't stop, I soak silicon for hrs in soapy water. If that doesn't work, I boil the silicon parts in distilled water for at least 30 mins. If that doesn't do it, I toss the recalcitrant piece and use a new one. Timing seems to vary quite a bit...at least it did with my OptiLife and now with my Hybrid.