Clinics and group workouts are curious things. They're supposed to be an inexpensive way for students to get some instruction & structured practice, as well as meet other players. Unfortunately, inherent in the format are some really huge pitfalls that have to be carefully navigated around in order for the students to get the most out of the clinic/workout.
* High student-to-pro ratios make it nearly impossible to give much (if any) one-on-one instruction without holding up the group, and without this much-needed instruction players often progress slowly (if at all). Trust me, finding the balance between helping individuals and keeping the group moving along is extremely difficult. I often error on the side of helping individuals though -- and have been deducted points on my USPTA certification for doing so!
* As mentioned in an earlier post, sometimes the perceived need to go over every single shot disallows students from becoming proficient in any of them, especially the basics. Doing fewer drills but for longer duration might help get players grooved with their strokes, but it would also bore some players and make them feel like they're not learning anything new or working on what THEY want to work on. There is no easy answer here, and the key is striking a balance between spending time on perfecting one or two shots or working on all of them, while keeping whatever you do fresh and engaging.
* Again with the high student-to-pro ratio, pros seem to have no easy way to satisfy everyone's needs when it comes to hitting balls. A pro can feed a small number of balls before rotating, to keep the players from standing around too much -- but this often prohibits students from getting into a groove. Or the pro feeds for longer to each student, which leads to students standing around for too long watching. Or the pro can have the students rally with each other, which may or may not end up being productive depending on the rallying skills of the students. A mix of feeding drills and live-ball (both cooperative & competitive) seems to be the best way to go IMO.
* Clinics/workouts with a large variety of skill levels allowed have an additional burden of trying to find a common denominator amongst the group without alienating everyone in the process. Make it too easy or dumbed down and the experienced players will get nothing out of it. Talk over the newer players heads too much and they'll get frustrated AND get nothing out of it. The best solution seems to be to try to regulate the clinics/workouts so that they are divided up closely according to skill level so that level gap becomes less of an issue.
That being said, I think in most cases clinics/workouts are worth the money. They're much cheaper than private or semi-private lessons, they can provide instruction & practice that you might not get on your own, and they are a great way to meet other players. If you have a good pro running them then they are
definitely worth attending as he/she will be able to avoid a lot of the pitfalls of clinics/groups that I mentioned
Final thought: Don't expect a clinic or group workout to be the cornerstone of your game's improvement. While they can be helpful, you still need to practice & play matches on your own time. If you have specific technical things you need to iron out, take a private or semi-private lesson to get yourself back on track. Clinics and groups alone (no matter how good they are) can't take the place of private instruction, repetition through practice, match experience, etc.