Rocker cover gasket

I’m not sure if it’s just me but my rocker cover gaskets front and back only seem to last around two years before they leak.
Does anyone else experience anything like this?
I have torqued the nuts down properly as I know over tightening is the best way to crush them. I’ve used heat resistant silicone as well on the last time to try and get a good seal. I’ve got stainless after market exhaust manifolds which seem to chuck out a ton of heat and I wonder if that’s affecting things? Anyone else have this issue?