I decided to try making a small day timer
In which you only carry around three months of days at a time.
Each page is one day
at the beginning of the year you carry around January, February and March.
Here are the other nine small booklets for each month
At the end of January,
you remove the filled January booklet,
move February and March forward and add April to its place.
A small day timer
that is easy to carry around,
and still contains lots of space to write