Except for very soft gelatenous mud, I prefer my spade as a primary
anchor in all other bottoms.
I was anchored on nite in a contrary strong tidal flow versus a
contrary and unstable strong wind which made the boat do a 360 every
3-4 minutes; the anchor reset itself in hard sand every damn time. When
the flow finally stopped I found myself less than 50 ft. from the
original spot that I had anchored - probably resetting over a hundred
times.

For very soft mud, I have difficulty setting it; in spite of letting it
'settle-in' before pulling strain on a very long/shallow scope.

I have a 24,000# boat and use a 44# steel Spade. I probably should have
gone to the next larger size to better handle soft mud. I carry a large
danforth and use that for soft mud bottoms; otherwise, I use the spade.