I use a binder along the 43 folders concept from GTD: 31 sections for the next 31 days, 12 sections for the next months. Every piece of paper that requires action on a particular day gets put into the binder in the corresponding section (daily if less than one month out, monthly if more).
Every morning, I process whatever awaits me for this day and shift the section separator to the end of the folder. Sometimes I don't manage to finish a task - such tasks get refiled for the next day. This happens sometimes to the task "do sports" - for which I have sheets of paper showing the opening hours of my gym and the local pool in my binder.
When a new month rolls around, I get a lot of paper that was filed for this month at some time, but not for a specific day. I do a mini-review and resort everything to the appropriate day.
This also works for recurring stuff. For instance, I have one paper sheet with birthdays that gets refiled over and over, always to (next birthday minus three days), so I have time to send a card. Same with reminders for quarterly payments etc. And the checklist for the weekly review, which I refile for the next Friday whenever I'm done. And the opening hours for the gym and pool, see above.
Finally, I also have Waiting For, Maybe/Someday and similar sections at the end of the binder, where I note or file stuff like this. I revisit these sections during my weekly review. Something like this should also work for a What I Did And Why or a What I Didn't Do And Why section for you.
The main advantage of the binder over actual files is that nowadays, I really have a lot of electronic and less paper stuff (I have a similar structure in Outlook), so real physical files of the type recommended by GTD would be overkill. In addition, I can take the binder with me when I travel.