Shipped in v1.2 (just went live). You were right that the upgrades weren't doing anything you could see - by_george341 pinned the cause exactly, so I reshaped the soil-hardness curve in the deeper strata. Buying an auto-dig tool now gives a real, visible m/s jump at every depth instead of fractions of a meter that round away. If you grab a fresh run (or reload your save), the rate should actually climb as you buy now. Would genuinely love to know if it feels right this time - and thanks again for flagging it.