How do I fix badly degraded soil that has me stumped?

You understand soil well now. The ordinary work no longer puzzles you. It is the badly degraded ground, the complicated cases, that still defeat you. That is not a limit of your ability; it is the honest difficulty of land that took years to break down and will not be read at a glance. Degraded soil is a knot with many threads, chemistry, biology, history, water, and no single fix touches all of them. Part of mastery here is patience: accepting that some ground heals over seasons, not days, and that your job is to start the recovery, not to force it. Nature keeps its own clock. One step: with the case that stumps you most, test and change just one variable, then watch what the soil does over time. Let it teach you. The complex situations give up their answers slowly, to the person willing to observe rather than rush.