A lot of us are notoriously bad at time management, so one way to manage it effectively is to note things down in a calendar. It’s something we can stick to.
I have never used a digital calendar for time management - I never liked the lack of a completely bird’s-eye view of my months, I never liked that color was the only way I could distinguish events from each other, and I never liked the fact that digital tools are so notoriously rigid in what they can and cannot display as corollary information. I pin and clip things to my paper calendar. I can very easily look at the rest of my year without a single swipe or click, and everyone in my household can be updated on the schedules of everyone else without the need to look at a screen, befriend contacts, sync accounts, or import this, that, and the other thing. I don’t understand how anyone can digitize their life to that extent and make it work!