I have never, ever cleaned a pit back down to clean or worse, to bare
metal inside.

I only knock off any loose scale or flakes that might come off during
cooking. That's all the way from my old brick pits, my barrel pits,
all the way to my offset cooker and WSM.

As a thought to add to this, when I called Weber for a new grate for
the WSM, I remarked at how stingy the smoker was with fuel. They were
delighted, and the lady on the phone told me Weber didn't consider the
WSM seasoned properly until it had a good coating of "stuff" from
cooking in it. She promised me that the cooker would perform better
in all aspects of heat retention, temp management and fuel
consumption.

Damn if she wasn't right!

If you have loose stuff, just flake if off with a hard bristle scrub
brush and call it a day.

Just my 0.02.

Robert