I made December all about portraits as it is a people time of year. I did not sketch as many different people as I imagined , my husband was sketched quite a few times, but then he is in my life a lot so it makes sense looking back.
From focusing on portraits, it was easier to decide what to draw day to day, and it did help to make me feel more confident, having that practice. I was thinking more about how to draw what I was looking at, than what to draw in the first place.
So I think I would put a theme on another month, it was a help not a hinder.
Now into the new year and new Sketchbook !
good sketching to you