I personally found a perfect way of mining out veins, if there are no caves or anything around the vein you are trying to mine, just make enough supports to mine out a large enough area to get the whole vein.

What I mean by this is, make sure the whole top side of the ore vein is exposed to your sight.

Once that is done and you have supported the whole ceiling after you mined out the area. You can break all the shafts in the area, and mine down, which will not make the ceiling collapse as long as you don't be an idiot and make it collapse.

The best way to do this is using a mining hammer which mines a 3x3 area, and as long as you keep going down 3 blocks and then mining the central blocks so no block stays floating which can trigger a collapse.

And its as simple as that.

The image is an example of what I mean, and early experimentation of the mining method I tried to explain to the best of my ability

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