by CTKShadow
As promised: Advancing digging requires three things to succeed:1) Sufficient coins. This is the most obvious factor, and why Halflings and Alchemists almost always advance digging.
2) Sufficient worker income from dwellings. This is difficult, because having many dwellings requires already having procured many hexes. It's basically never worth advancing digging if you then have to procure workers from act3 to do your digging, because act3 only costs 2 power less than act6, and when you consider the costs of advancing digging (10c,4w,2p) there is basically no way saving 2 power even several times is worth that many resources. This is why advancing digging to dig with engineers is basically never feasible.
3) Sufficient time. I'd wager that if you add player count as a variable, advancing digging is relatively stronger in lower player counts than it is in higher player counts. After all, how often have you had the resources to advance dig in a round, but have to do a hard dig or take act5/act6 before advancing digging in order to secure a hex in time? If you play the digging factions with any regularity, you know what I'm talking about. Often the biggest challenge with advancing digging is that it's just too slow. But this is assuming you're competing in the tournament format and meta against the fastest economies (Darklings, Engineers, Cultists). If you're playing a three player game, you'll get more resources more reliably from power actions and can generally take longer to secure your hexes, making advancing digger a sounder strategy.