As someone who makes the main part of their living giving workshops (albeit for a lot more reasonable price) I can only say it depends. I stopped advertising the much more lucrative 'group' workshops in favour of individual workshops for the simple reason I enjoyed them more and the student gets much more out of it. They get a full day that centers around their needs vs. trying to meet a set of objectives which might or might not fit the individual.
I still do groups on requests but I make known my druthers and I'm okay from there. But it's very tiring not to mention a bit hectic trying to keep track of 4-5 students at a time and provide them meaningful instruction while doing so.
A quality workshop, imo, should ideally be centered around your skills and where you want to go. Often times there's more between here and there than a person realizes, but properly explained they can understand why. Like math, certain gaps in knowledge must be addressed before going forward. r If at all possible gear should be made available for a student to "experience", this by itself can save the student more than the cost of the workshop.
Most of all, be sure you can talk to the instructor. If their replies are too abbreviated and don't answer your questions consider this might extend to their teaching style. Ask a few questions when feeling out a workshop and see how the instructor answers them and see if this is compatible with your learning style. Even if you understand the answer say you don't and ask the to explain again, any decent instructor should be able to explain any concept 4-5 different ways and switch between them on the fly as your eyes register understanding (or not).
And do keep in mind.. you won't learn in a single day what took a pro ten years to learn. If you're lucky enough to get a good instructor you get on well with, and they'll center the class around your needs, keep your expectations reasonable. It's far better to spend 30 minutes on a single concept and fully understand it, than to spend the same time on 4-5 concepts and not be sure you understand.
Workshops above all else should be fun. If you're not a pro them you're an amateur and you're doing this for recreation/enjoyment/fun.. so it should be. It should also be safe which is a big consideration where I hold my workshops. Vehicles should be insured, medical insurance available if not provided, and a really really good instructor.. they'll have batteries for your camera charged and in their bag just in case.. ;o)