Does logging your studies help?

Yes! Whatever form works for you, but you should definitely track your work in a systematic way. That's how you know where you are making progress and where you aren't. Where you are making progress, keep doing what you're doing. Where you aren't, you'll need to find new ways / strategies / things to do.

For every question you do - what did you get? how much time did you spend? if you got it wrong, why did you get it wrong? what do you need to do to avoid making that some mistake (or those mistakes) in future? (and then go do whatever that is, of course.)

I recommend that my students also take 5-10 minutes at the end of a study session to write down what they learned today about themselves as GMAT test-takers. What's getting better? What's still problematic? What do they want to review in a few days or a week or two? What do they want to concentrate on for the next few days based on how things went today?

Then, when you start a new study session, glance back over the notes from the last 2-3 study sessions. Use those to help keep yourself on the warpath!