I'm taking Jason Seiler's course, and while we're only on Week 3, I've already noticed an improvement in my caricature work. Probably because the guy is an absolute slave driver. :)
While I'd like to spend more time on my editorial cartoon caricatures, I've often got to get them done and sent out in a day or less. This one took about 8 hours from sketch to completion but I enjoyed working on it so much that I could have easily spent another day on it. If nothing else, I'm more confident getting the likeness down in a short time.
Here's the reference photo I used (resolution wasn't good)
...the final editorial cartoon...
...and a closeup of his noggin.
Having a great time so far.