Why is the CW is airing repeats so early in the season [next week Vampire Diaries and Nikita are repeats]? Just as we get into the show, we have to wait two weeks. Would this lose viewers as they'd have to couldn't be bothered to keep up with all the breaks/gaps?
How often will these "gaps" be before mid-season?
The CW has 9 scripted shows (assuming they all run the entire season), that they'd normally order 22 episodes of each, and all those shows started at least a week "early" (Nikita and Hellcats started 2 weeks early) during what is normally a 35 week season (although the last "week" is just 4 days long).
Since the CW doesn't do sports, specials, or mid season only programming, that means that during the season, those CW scripted shows will have 14 (or 15) weeks of repeats. From now on, the CW will mostly air new episodes during the local sweeps months of November, February and May, but outside of those times you'll see lots of repeats.
How long might these repeat gaps last?
Last season is not a great example for this season because The Beautiful Life cratered after just 2 episodes (which didn't happen this year), but the CW didn't air a single original scripted show episode in the five week period between December 14, 2009 and January 17, 2010, and many shows had even longer repeat gaps around that period, some presumably trying to avoid getting crushed by American Idol. 90210, Melrose Place, and Gossip Girl all had 12 week repeat periods from mid December through mid March.
Why do they do it this way? Why not program the gaps? Or produce specials?
You'd have to ask them, but my guess is that since the conventional wisdom is that the CW runs at an operating loss, and the corporate parents (CBS, Warner Brothers) make it up from licensing the shows they produce for the network and their DVD sales, there is no financial incentive to produce gap programming or air specials.