This is one of the things that frustrate me about Debian based systems. I know most distributions ship with lots of different tools to do the same job and you pick the one you like. But with something as fundamental as system timers it just feels wrong to me - when I want to change the timing of something I first need to figure out is the cron job real, or just a stub referring to the systemd timer, or visa versa.
So for a while I had removed cron from all my systems and fully committed to timers. Now I've decided I don't like systemd and gone fully the other way.
I know it's not that bad, but that's the way my brain works - and I can remember getting really screwed up with some early Ubuntu systems.

My brother in-law was a vet and he used to say human doctors have it easy - they only have to learn one animal.