You have as many next actions as you have, and, yes, you should be looking at everything on your Next Actions lists (by context) when you have any discretionary time, and you are in that context. So, yes, they should be reviewed sometimes several times a day. You need to relate to your Next Actions lists as your “real to-do lists” as much as your calendar, and save the calendar for “they-die-if-not-done-that-day” things. It’s good to put the due dates on the actions on the lists as well, as an extra precaution.
The Weekly Review ensures that you “hard-wire” your intuition to be making quick judgment calls, day-to-day, minute-to-minute, using the lists as a focusing tool. Much of what happens with and around you during the week won’t be on any of your lists–it’s the ad hoc stuff, but having something that represents a stable inventory as best you can define it, to work against, is the only source of stability.
If you need a “weekly priorities list,” in addition, to help you stay focused, fine. Sometimes we need that kind of thing, though most of the time, not.