I tend to look more at days than at individual trades. Win days vs. loss days, net win day %'s, gross win day %'s, etc. Everything is logged as far as transactions are concerned, and I can 'data mine' later if I like...however I tried that and it did what you might think: confirmed what I already knew.
I thought you meant 'journal', as in, 'why I took this trade.' I keep one going during the day, but not about each individual trade. Just about the general feel of things, a particularly good or bad fill, rants, etc.