Not just for the sole purpose of revisit them later but I'm doing my log for my future trading decision and since trading requires history, this can be a big help for you to know your next move in trading by just looking at your log sheet.

You have to keep yourself on track, and put everything under your control, don't just record your favorite forecasters prediction its better to create your own, focus on your own and succeed on your own. Never rely to anyone when it comes to investing, that's risky.