Hence scheduling, which leads to agendas, the midway point between a calendar and Todo list.

I used to use an org agenda view for this, now I just use a caldav calendar and trillium. In the morning, I check my to-do list, which has been being created for this day over the last couple weeks or months, I look at my agenda to see what meetings or appointments I have, and I slot todos in between them. I might even be doing so for the whole week or month, moving tasks around as needed. I take a look at my week and month todos and see that something is due in two days so slot it in for today. Similar to how a project manager might do with sprints and tickets I guess.

I think the critical aspect of any functional Todo system is active review, at least daily if not more so, plus regular weekly and monthly cleanups.