Placio
I think the difference is that your DP is based on your highest skill so practicing a lower skill will take much longer to remove DP. A single DP for me goes away after 5-6 digs of q250 mats. However if I dig q100 mats in a region that I have not mastered, even though I am getting more xp per dig, the DP barely moves. :(
I wish I could remember where I saw it, but I read somewhere that that is, in fact, the case.
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