Get Everything Done

No system can handle it all, I guess. I notice I break the sequence in AF4 whenever I have a) parallel tasks or b) context dependent tasks. Let me explain:
a) I've run through my open list, and am on e.g. my second from last task. While I'm there I notice that there's something I could be doing simultaneously, which is higher up the open list. Technically I'm not supposed to go there as the open list is only worked through once, and then it's back to the closed (aka backlog) list. If I go there, without actioning anything in the closed list, technically the closed list is up for review. A specific example. I've reached the second from last item on my open list. It says go for a speed walk. I can see there is the possibility to handle a few phone calls while walking, however these calls are higher up the open list, and I'm supposed to do tasks only in the closed list. Context dependent example b) I've driven into town to pick up a cake my wife's ordered. While there I could run a few other errands, but they are higher up the open list. However, it would be a shame to go home without having done the other items, as I'm saving a future trip.

I realize Mark says use common sense. Doing so may however result in some slippage in the application of the sequence and I may end up not following the procedure when it ought to be followed, as I've already broken with the system on these exceptions.

Anyone else with similar experience? What other exceptions have you found to the AF4 sequence?

I think Marty H's answer to the post "Doing two taks simultaneously from AF4 list" is relevant.
He wrote:

I think this is a matter of trusting your intuition and not making the system too complex.
If you are in the middle of a task, anything you need to do to keep working on it "for as long as you feel like" is part of that task. It is no different than adding it twice. When you get to it (or just notice it) on your list, cross it out and take credit for doing it.

In your case, I think that if your intuition says that "in order to do this task for as long as I feel like it, as effectively as I can, I want to do those other tasks that I know are in the list, but want to check I've remembered them all".
In other words, you're not breaking the rules if you're specifically scanning the list for things relevant to the task you're working on. You would be breaking the rules if you just start scanning for random items and doing them: that's called a 'to-do list'... :-)

For example, in my list, I mark "errand" items with a small car (very dodgy drawing) which means when I'm going out, I'll very quickly scan the list for the other 'cars' to see if there's any other errands I can do. It's the same as having a separate 'errands' list, but it's seamlessly integrated with the whole list. Having the icon means that my eye isn't distracted by other tasks since I focus on the lines that have the icon on them.

Hope that helps.
Ben.

Yeah, I'd not worry about hurting the system ... all will be well. Keep in mind that the system exists to support the doing of work, the doing of work does not exist to support the system.