The workshop houses 7 lathes of which three are standard commercial woodturning machines. The headcount limit is set primarily by the size of the building itself and the amount of time clients can wait for a turn. I have never gone above 6 with each machine having one doing and one watching with me initially demonstrating then moving around coaching as necessary. 4 is a better group size in terms of getting a good view of the demonstrations especially as when the demonstrator machine is used as well all can work at once.
Group courses work to a fixed syllabus. You can learn as much watching another beginner as you do doing it but once watching is enough so I rarely take larger groups except in a college evening class environment.
The attraction for groups is that my wages are the same regardless of group size so with 4 persons, each only pays £7.50 per session plus £2 a head for materials. Group course fees have to be paid for up front as I can’t take a pay cut if one drops out. These courses quickly take on a club feel and groups are often reluctant to stop once they become established. .