I may misunderstand, but if you have a Phone context or list, wouldn’t it contain the following next actions (among other items):

• Call Handyman at 555-5555 to arrange appointment for X.
• Call Handyman at 555-5555 to arrange appointment for Y.
• Call Handyman at 555-5555 to arrange appointment for Z.

The next time you look at your phone list, if you look over the entire thing before deciding which calls to make, you’d either call Handyman and set up appointments for X, Y, and Z at once, or edit the items down to one next action:

• Call Handyman at 555-5555 to arrange appointment for X, Y, and Z.

This may miss the point, since I’m basically advocating moving the process you fear missing in the weekly review into a process on the working lists themselves.