AND
As far as sealant goes
FWIW
Years ago I checked the valves on a gen2, all in spec, no suprise.
Replaced valve cover with new oem Suzuki gasket, everything clean, torqued to spec, and in sequence/pattern.
I did an 03 gsxr600 a few months ago, exact same thing...and the valve covers on Both bikes leaked oil !!!
Especially at the cam plugs, but also rear near center.
Neither gasket was installed incorrectly, pinched or damaged in Any way.
So, for both, I removed them, cleaned the new gaskets again, and applied a small amount of sealant and torqued.
I let the sealant set up overnight.
Cranked and rode the bikes, and zero leaks.
So, good luck if your bike needs the engine opened and you're against sealant, because you just might have a leak you otherwise cannot stop.
And no, each valve cover had never been off before, and was disassembled cold.
I go by service manuals and do not cut corners.