The big difference between 35mm and 4x5" negs is in the level of details. What looks like an evenly grey area (and is evenly grey on a print from a 35mm neg) might be a maze fo high-contrast complexity on a 4x5" negative.

I had a problem with a fuzzy 18% grey area on one of my pictures - whatever I did it was still a dead boring fuzzy area of 18% grey. That included changing the contrast, printing daeker, printing lighter, toning, and just about every trick except diffusion.

Then I finally got the bright idea of examining the offending patch through the grain focussser I never use: It was a very high contrast tuft of grass. Printing larger resolved the individual grass blades, and suddenly it was interesting instead of fuzzy and dead boring! It printed in almost total black or white, which is why all my adjustments failed to change anything...