It sometimes can be, as it is now, because there are no or very few shows opening, but there are often times where productions don't get their CDs actually released until summer if they opened in the spring, leading to a rush of new releases in May and June (that's the way it was last year I think).
As for re-issues, when is Decca broadway going to start reissuing old recordings again??? They have so many great recordings in their catalogue, but they haven't done a reissue in years upon years.