Nice group of planets.
(thumbs u
You are correct, with FH it seems the brightness of the colors comes and goes throughout the runs. Certain books are almost never seen with a "fresh and bright" cover while others like the ones you have shown just pop off the page.
For example, with Planet comics it seems to be strong with issues up to 10, but have seen many light books for 12-19, but around 20-25 strong colors then down and back up with strong coloring starting in 33-39.
Long story short, Adam I think you are spot on.