How to schedule tasks on Linux

Schedule non-trivial tasks to run whenever you want

Nice! But how can I use it? What are specific use cases?
Or why should I even care about it?

Well, every company I worked before had its routines. Daily, weekly, monthly, on even non-periodic. Most of them were simple tasks you could easily manage through Google Calendar, Wunderlist, Trello, Slack, or whatever, just choose your weapon.