Checklists make sense for repeated things, but don't seem right for one-offs. In practice, what you are doing is replacing a hierarchy of tasks (or even a flat list of tasks, which does seem a bad idea) with a hierarchy of task lists, where the the checklist (lower level task list) is identified as one task in the higher level list.

If your task manager can show this, another way would be to have each task in the list show its hierarchy, so you can see that "Jeff re next week's meeting" is part of "Define strategy for next year" (or whatever), but I suspect that will soon get very clunky.