Agenda is working exceptionally well for my ADD mind; I prefer to keep an accessible master list of projects, and then keep a sort of continuity log, or change log**, to track work I’m doing on an active project (I’m a writer with a day job.) The GTD method of keeping a monster list of stuff I needed/wanted to do used to make me want to run away from it rather than tackle it. (I can’t hide task lists because I’ll forget I ever created them. ADD makes me forget what is not visible way, way too easily.) And yet….
I, too, need a way to keep a list of tasks & projects I’ve completed & can refer to if necessary, but kept separate from the main views. I realized I could use subcategories for this. I put major goals, such as my current one, “Publish Oral History Research Project" into categories of their own, and regular projects into catch-all categories such as “Household.” I’ve created a subcategory for every category & called it Archive. Then I’ve put a new project into the Archive called Completed Tasks, & when I’ve checked a note as “done” I move it to the Completed Tasks project for that category.
I suppose there are other, less granular, ways of doing this, e.g. creating an entire Category for Completed Tasks from all projects but I like keeping related material all together.
Anyway, so far so good. Haven’t run into any hiccups and, in fact, this non-specifically GTD app is working way better for my ADD-friendly version of the GTD method that any of the other apps with GTD workflow built in.
** If I can keep track of what I’ve done, or what part of a project is currently in progress, I always know what the Next Action is. (My day job causes big gaps in my personal project timelines sometimes.) Looking back at how far I’ve come is SO much more motivating to me than looking at how much work I still need to do. YMMV, of course