We did a winter mountaineering course in Gredos last year and it was great. We were 4 friends with different experience and technical level, but common goals. This background, far from hindering the course, made it much more interesting and productive, fitting perfectly to our needs. Not too short, not excessive.
In fact, I would do it again, given the experience and good work of the guides, who knew how to adapt at all times to our needs and peculiarities as a group.