I used the Pathology section during my Pathology class (which luckily was right before I started USMLE prep). If you haven't already noticed, there are tons of images! I don't think it would be a practical use of your time to go through it during your USMLE prep, it would just take too long.
The only part of webpath I used for USMLE prep was the AIDS section because it had a lot of Micro images.