Hi Dave, for wet-on-wet or alla prima you don't need to worry about the rules as paint is applied in one sitting. So all pain is intermixed and dries together as uniform layer.
The rules you mentioned become important when we talk about academic painting and layering. In this case you start with underpainting most times (burnt umber= quick drying), then add medium tones, then do glazing to enhance parts, etc. So in general 3-5 layers. Following rules will prevent upper layers cracking and will keep painting in tact.
This website is a source of wonderful articles about oil paints, mediums, etc. Please go ahead and investigate. https://www.jacksonsart.com/blog/category/art-technique/oil-painting-art-technique/
I recommend as they deserved my trust over last couple of years since I jointed oil painting.
Fat over lean = more oil over thinned paint.
Thick over thin = a lot of paint (impasto) over very thin layer of paint.
Bob indeed breaks the rule fat over lean when he does branches on the trees, it did not work as I wanted for me though, thus I started thinning paint for brunches with thinner and with oil together. I found for myself that paint thinner cuts through the layers and did not like that while with oil added I have more flow and control over brunches.
However, as folks said above in general consistency of BR paints, thus BR method somewhat follows the fat over lean and thick over thin rules.