Activa LT cushion, how long before u lose seal, change it?

[goose]

I wash my LT when I remember -- and I've got ADHD....
When I do wash it I use vinegar and dish soap.
I disinfect it every morning when I'm sick (like the past 5 days) just to get the little buggers out......

I've had my LT about 3 months (Had a regular Activa before that 5 or 6 months). It seems to be sealing ok still. I'm due for another mask, but this time I'm going to get a Quattro FF mask for those days when I can't nose breathe.....(my HC431 is, for me, a piece of crap. I know it works for others!!)
All of that said, I've been told that the silicone membrane that seals the masks does eventually wear out. Since I get a new mask every 3 months, I've never used one long enough to wear it out -- but it looks like I'll have 6 months on the LT before I replace it.....

cheers
goose