At least for me when friendships/relationships become transactional it loses a lot of the value. This method of staying in touch feels _very_ transactional, and I just imagine sending some random person you spoke to a few times in high school/university a message every 6 months - 1 year.

Some people aren't meant to be in your life forever, and that's okay! However, there the people you choose to make time for will stick around.