I found this overview of common film processing problems helpful. It's by Ilford, and it's got pictures of negatives and what they will look like for a whole host of common film development issues.
This is super helpful as I attempt to come up with a new developer recipe for my 4x5 experiments. I am using caffenol, but I haven't seen much information on using caffenol with continuous agitation systems. Stock caffenol formulas are pretty well characterized for intermittent development, or even stand development, but my 4x5 setup is a rotary one.