The application of copper spray (or any other kind of added sealer applied by the installer) is a complete waist of time (and expense). The Fel-Pro gaskets already have a micro-sealer, which is furthermore an anti-stick coating for clean and easy gasket removal if/when needed. You've already paid for it when you purchased the gaskets.

In more recent years, some manufacturers of MLS gaskets have a supplementary sealer additionally applied at the end of the manufacturing process.

For single-shim old-fashioned original embossed metal gaskets (such as the very old and original BB head gaskets), that is where a thin coating supplementary sealer could be used. And the copper coating is marginal... a "hi-tack" spray coating is better for those as it will have slightly better viscosity.

IF the surface finishes are very good, and without pitting or corrosion, then realistically, there's no need for supplementary coating to be applied at all.