Having fun with destructible meshes but can't figure out how to selectively destroy

I’m looking at the options for destructible meshes here:

and I see more than a few options that would allow me to customize the way they work, but…

in game, it seems that after the first time a destructible mesh activates, it becomes invincible and can’t be further destroyed.
Furthermore, when I tried making a really big one, setting the damage threshold didn’t seem to affect anything at all; the whole floor blows up at the slightest touch of a bullet.
But I’m working on that, I suspect a few other problems may be contributing, since it’s invisible as soon as it fractures anyway.

What I really want is for the destructible mesh to only blow part of itself per blast, and for the pieces to fly up as shrapnel, and of course not cause chain reactions when hitting the ground again. (that could get out of control fast)

Does anyone have a very rough and simple way to explain this? I figure it’s just a matter of balancing the numbers right, but I don’t think I really understand them because I keep making adjustments and seeing the exact opposite of what I’m intending or no result at all.

What I THOUGHT I would do is this: set the damage threshold, lower the damage spread (it literally says that it is the exact thing that I’m looking to control but it does not do ANYTHING as advertised), and lower the damage cap.

That SHOULD have made it possible to only poke a tiny crater in the surface and have shrapnel appear, but instead, no matter what, every time a destructible mesh is activated, it always, always destroys into the same chunks and the whole thing is dismantled.

Not that I can’t work with that, but there’s got to be a way to make it work as advertised.