I did extensive testing with throwable dynamite before using it to blast out the large pit that became my ultimate base. I found that three bundles of dynamite for each blast was the sweet spot for making the biggest hole with the least dynamite.
For a vertical shaft, simply dig down 4-5 blocks, get out of the hole with a sacrificial wooden ladder, toss two unlit dynamite in the hole, light the third one and toss it in.
For a horizontal 3-block-high tunnel, dig a blasting hole out of the middle and top blocks of your tunnel in progress, two blocks in. Then it’s easy to light and toss in a single bundle of dynamite, wait a moment, and press in to repeat.
Naturally in either case, you’ll have some leftover debris in the form of destroyed stone to clean up. The timed charges look like they’d be the replacement for placeable dynamite, but their blast radius seems to be unsuitable for this purpose.
devtrackers.gg