For mining landmarks why not follow the right hand rule? Place torches on the roght hand side as you're exploring away from the base. When trying to get back to a junction or your base always look for the torches on the left.
I don't think you understand the nature of the problem I was posting.
It's not about exploration. It's about clearing a large ore vein, not missing any ore, while keeping the mining site comprehensible. It's about clearing an area, not trying to find my way back to base. I don't have any problems with the latter.
If I mine out part of a vein, and then return later, there's always a question of which parts of the vein are exhausted, and which still need work. Even during a single run, it's easy to overlook some obscure corner.
As mining progresses, the worked vein doesn't retain any kind of order, no matter what pattern you use. Branch mining is simple in structure, but once you knock a bunch of big holes in the walls between the branches from removing ore, it can quickly become a random mess.
Part of my problem, historically, is that I tended to do what we call a "greedy algorithm" in programming. Basically, I'd dig out any piece of ore I saw, even if it was above or below my current level. This often ended up with a 3 dimensional maze that was hazardous to navigate because of long drops. The solution to that is simple - don't dig out any ore below my current working level, no matter how tempting it is.
The simple solution to all those problems is to remove everything. If there's a block left on the current working level, it's not done. Seeing which parts are incomplete is trivial, and navigation's not a problem because the final result is a big open space with no obstacles.
The problem is that this is far more work than necessary. I dig out a lot of stone that I don't really need to in order to expose ore. More efficient methods, however, leave lots of stone to block line of sight, so I can't just glance around the site to see what area still needs work.