greetings folks!

Those of you who regularly use preformed silicone earplugs (doc's pro plugs, for example), how long do they last you?
When is it time to replace them?

I read that goggles (which have clear silicone on them, which degrades in the same manner plugs do- going yellow after a while and sometimes leaking) should be replaced after about a year of regular swimming.
I kept mine a lot longer than that because they are out of production and fitted me so well.

How do you do it- do you throw your stuff out as soon as it isn't completely watertight anymore?