Its presumably not real hours, but, rather, block-hours, that is, the number of blocks that ought to correspond to two hours if in fact the blcoks were being created at the target rate... In other words, 120 minutes divided y 4 minutes, thus every 30 blocks. When blocks come fast, it thus happens faster, when they come slow, it presumably would come slower... Same applies to years in bitcoin's supposed four years between block reward changes and so on and so on...
-MarkM-
Mark, a quote from the OP:
Twelve retargets per day with a maximum swing in either direction of 25%
Sounds to me they are talking about real hours not blocks.
Every coin talks about either "retarget every x hours" or "x retargets per day/week".
That's based on the amount of blocks between a retarget.
Blocks per retarget * expected time between blocks = time between retargets.
So when diff and hashrate are more stable, you will see 12 retargets a day.
But while hashrate is still growing, blockrate is faster what makes time between blocks shorter and retargets faster.
