I have a desk calendar at work, for meetings and school happenings etc. I also have an agenda which I have all that plus specific times/periods where I am meeting students. I do put personal stuff in both.
I also have a calendar at home on the fridge, no work stuff unless it is after hours, like parent/teacher interviews, open house.
My phone calendar is basically used when I make an appointment so I don't forget to transfer it to the paper ones