In the good ol' days, Doctor Who was releasing 30-40 15-20 minute episodes a season. Which is a lot. I recall a TNG special where the cast was talking about how stressful it was to shoot 20-24 episodes a year, in one week blocks - which could mean for an intense episode, 10-12 hour days.
Certainly producing fewer episodes a year means more time to polish scripts, being able to take longer to shoot a single episode - 2, or even 3 weeks of daily shoots per show would be a lot easier on the cast and crew. In an effects heavy show like DW it gives them more time to polish up in post (thinking of the Adipose episode, Doctor and Donna hanging on the scaffolding...).
It also allows fore more elaborate "on location" episodes, especially when the entire premise of the show is that you can travel anywhere in time and space. Even an expensive TV show can't afford the budget for major fx like a feature film, so you cut corners using every filmmakers tried and true techniques.
In The End Of Time, when the Master gets kidnapped by ninjas, and gets roped to a helicopter; the crew used a truck with a cherry picker, some floodlights and fans to sell the effect.
So yeah, 13 a year maybe a lot, but if it's only 10 a year I could live with that. But I kinda lost interest in DW over the past few years and it's hard to get back into it.