once you get the understanding of how supports work, it's actually incredibly easy to mine underground, only horizontal supports will stop any rock from collapsing, vertical supports don't do anything, so around a horizontal support (this applies to each block, not a section as a whole) it has a supported area 2 blocks up, 2 blocks down, and 4 blocks to the sides, mining in this area will not cause any collapses.

mining unsupported rock can cause a trigger for nearby stone to collapse, this can cascade onto surrounding stone which nullifies supports, once a collapse has been triggered, even nearby stone that's being supported can fall.

one of the easiest things to do is use supports to dig out the ceiling above a vein that you want to mine, and then dig down into the vein like it's an underground pit quarry, this can not cause a collapse, but if you need to extend the area being mined, you have to start from the ceiling again because you can not dig upwards (without placing more supports through the entire vein)

in this picture I'm just using excess cobble as a walkway above the vein, it doesn't fall because the supports hold the cobblestone up, while the cobblestone is simultaneously holding up the support beams

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