difficulty adjustment timeframe? will december batch not be very profitable?

[frankbitcoin]

question for you all,

the december batch of L3's - isn't it possible that those could be 50% of the earnings compared to what we're seeing now?  We have a new batch from this month hitting customers soon.  Then the december batch.

Almost feel like it's not going to be worthwhile to mine whenever I get my miners since the Return on Investment might not happen for 6 months or more.  Almost seems to make sense to just hold your money as the actual coin and no even mine.  

What's the answer?  Any thoughts?