Some of us stick to the same size year in year out... never changing... But I've noticed a trend of a sorts, of a cyclic pattern of size changing... People downsizing because they are tired of lugging around an A5 and they move to a Personal. Or Personal to Pocket.
And then there are folks that seem to be moving in the opposite direction for various reasons.. not enough space being the most common excuse... I've not managed to work out over what the time interval is for people to go back to the size they started with yet!!
Have your changed which size of Filofax organiser you are using on a daily basis recently? And if you have why did you change?