I used M105 and M205 on both of my recent details and this advice is dead on. I always start light, and work my way up if needed. No need to waste the time and effort by doing an extra buffing step if it isn't needed. Not to mention the extra wear on the paint surface.
I had a few water spots on both that needed some 105 before the 205. But I only did the spots that needed it, not the entire vehicle.
I buffed my dark blue boat too and used 205 only for a few minor scratches.
No experience with CQ here. I used WG and Pinnacle stuff.