It is possible to book lessons for one person or more. An increase in the number of students reduces one to one attention. For this reason it is advisable to book several lessons, even consecutive, especially if the number increases from 2 to 3 otherwise it may be difficult to guarantee a rewarding lesson. It is also important that there isn’t too much technical difference between students (eg. A skier who has minimal experience would find it difficult to share a lesson with a complete beginner, or someone who wants to ski in fresh powder could not ski with someone to still does snow plough)
A mixed level group is possible for skiers new to the area and who want to be guided around the mountain to discover the Milky way for the first time.
Should you consider ski school group lessons? Why not? Obviously the instructor cannot dedicate his time to each individual student in the class like in a private lesson but if someone is looking for the social aspect of skiing, to spend time in the company of others then the goup lesson is perfect.