I've been noticing, specifically with minerals/ores and not with liquids, that they can tend to gather large deposits under buildings and other places where you cant mine, thus (i guess) trapping some of the available ore mass in places where it will never be exploited.

Liquids seem to run in different patterns, which is probably why they arent affected, or at least i havent seen them be affected by this entrapment.

over and out
-spider