DVE and adustments

Following the general advice on these forums, I bought a copy of DVE to calibrate my new TX32PS5.

I also have a Panasonic NV-VP30-EB video/DVD and Sky (not plus) connected. Because of only 1 rgb scart I have the sky going through the combi and the combi in scart 1. I get rgb on sky and when DVD is inserted it auto switches to show DVD which is also rgb.

The question is, playing the DVE disc shows various adjustments to colour, sharpness etc as well as brightness and contrast. Being rgb, the only adjustment is brightness and contrast so is that all that can be adjusted? Aside from geometry. I don't see the benefit of DVE for rgb situations as adjustment is limited.

Am I missing something here?

Would I need to run DVD through scart 2 (non rgb) to adjust the set for video viewing? Seems logical, but there again I'm new so may of missed the point entirely