What if you get stood up, or the person you're meeting keeps you waiting? I've known several executives who, although not practitioners of GTD, always kept a list of phone calls about their person (including number, name, and purpose) to take advantage of those little windows of time. Remember, GTD was designed originally for executives, so it takes your situation into account.Sure I have a cell phone, people around me and doing errands. But my executive world is so fast that I can't have @Errands. I'm always on the way to somewhere with no free slots to stop by.
And what about making calls on the way there? That's one of the most common uses of the @Phone list, which is itself one of the most common context lists: you can clip the headset to your ear and deal with one or more NAs as you travel.
That shopping list you mention is a context list. And your agendas for people you meet are also context lists. A context list is just a list of things to address when you're in a particular context, whether that's at the shops, travelling, or being in the company of a particular person.I have to schedule errands so I keep a shopping list for that scheduled time. The same with people. Either I schedule a meeting to discuss something I have on their plate or call them.
If you're meeting with someone, it helps to have on hand everything you need to talk to them about, otherwise you waste a lot of time having multiple meetings.
Also, if things change so quickly, do you have to cancel/reschedule a lot of meetings? That's a big efficiency drag in itself.
The WF list just reminds you about following up on things - it's a bit more flexible than tickling it, because (a) you might have an unexpected opportunity to follow up before it comes up in the tickler, and (b) you might not be in an appropriate context (whether time, energy, or whatever) to address it when you take it out of the tickler.I don't have @Waiting for, I prefer an active calling on a person, I could always tickle that call.
Also, if you're always calling out, you're losing efficiency - let them run around, and only prod them when needful. You'll get more done that way.
It may be the case that your situation is different, in which case you can do as you choose. But before you toss out the NAs with the bathwater, think very carefully: are you completely sure that you won't get any benefit at all from having your NAs listed and ready to go?You see I really have no contexts (if I have something it's scheduled), I have a long project list limited with SM list, and next actions vary in time. So why not to use project list as an action trigger?
Remember, too, that one of the benefits of GTD is the mental clarity: just about any GTD-er will tell you that there's a massive payoff once you get the hang of things. The reason is that your mental RAM is no longer jammed up with having to remember (consciously or sub-consciously) lots disconnected bits (such as the context associated with a particular project), and so the mind seems to work faster and much more creatively.