The first thing I noticed was that the Deep Mining research resulted in 50% of each and the <Iron ore/Copper ore/Coal/Stone> Deep Mining resulted in 80% of the specific one and 10% of the rest.

My line of thought was: "well, 80 + 10x3 equals 110, while the other sums to 200, which means that the specific one trades raw number to allowing you to be space-efficient in relation to the one you want, you'll have less resources, overall, but will use fewer constructions/space to get the amount you want for the specific one"

But, it turns out that the Deep Mining craft time is 4, and the <Specific resource> Deep mining is 7.1... I made a spreadsheet and found out that even for the Specific Resource, the <Specific resource> Deep mining is slower, and I actually tested in-game. I've put 5 Deep Mine, each with each recipe, and let it run for some time (with separate chests), something like 10/15 minutes.

When I came back, the basic one had about 200~220 of each (one machine summing 835) and the specific ones had 190~200 of the specific one, and 20~30 of the rest (each machine summing about 260~280).