Valve Cover Gaskets

I own a 93 Safari AWD. I was wondering if it is ok to just use RTV sealant to seal the Valve covers or should I buy the gaskets. My van had the rubber pre-formed gaskets and so did my my 91 blazer. Both vehicles the rubber gasket failed miserably. I prefer to use RTV sealant as I have never had any issues with it. Any ideas or comment are appreciated.

Thanks.

Provided the cylinder head and the rocker arm cover sealing surfaces are cleaned properly, the PCV system is working properly, and the rocker arm covers are torqued to the proper spec, the pre-formed gaskets will not leak. If one of those items are overlooked, they'll leak...guaranteed.