systemd timers are a cron-based workflow.

A cron-based workflow is when you periodically check for work to do rather than get notified that there's work to do.

Yes that's true that they periodically check for work to do, but cron is not smart enough to know whether a service is already running - a systemd-timer can base it's timer from the point when a service completes. I think cron just fires up a service unless you build in some logic to check if it's running

That's not really relevant. masklinn is contrasting periodic polling schemes like yours with using IDLE.