An annual reminder keeps time more reliably than it keeps affection.

A date in a calendar is very good at arriving and no good at caring. The message it produces is punctual and can be completely hollow, while the friend who forgets the date and rings in March because you crossed their mind has done the thing the reminder was standing in for. Systems keep time. They cannot keep the feeling that made someone set them up.

Keep the reminders, since forgetting hurts people, and add something the system cannot supply: one specific line about them, or a call in an ordinary week for no listed reason.