So, the big gap was between Christmas Special 2011 and the start of S7, not within S7.
And we have the same gap between Christmas 2013 and S8
The annoying part about that is it's the longest gap we've gone since the show returned in 2005. It's a longer gap than we had during Tennant's supposed "gap year" in 2009. Even more irritating is that the reason behind splitting the seasons was to cut down on the gap between seasons, and it's just increased it instead.
Oh well, I'm glad S8 won't be split and hope no future seasons will be either.