This morning, for example, the process went something like this: I recalled that I had meant to write an entry about something. Probably just what-I-did on Thursday and Friday. I'm pretty sure I went to the library both days; I know I went yesterday because yesterday afternoon I read (and enjoyed) Laurel K. Hamilton's Bullet in one fell swoop. I know I went out for a walk both days... I was pretty sure I hadn't written anything either day.
So I checked LJ, and found I had written an entry on Thursday after all, which jogged my memory that no, I had not gone to the library that day - I'd gone out, but decided to go see a movie (Knight and Day) instead of going to pick up my library book. Then I met my brother for dinner. A couple of fairly significant events that I honestly could not bring to mind until I'd gone back and looked at my journal. Reading what I'd written, then I remembered what I'd done after I'd posted it and for the rest of the day.