A small group is not a smaller class
A group of two or three private clients is its own format, with its own rhythm and its own risks. A coach who treats it as a watered-down one-to-one tends to teach the strongest person in the group, and a coach who treats it as a small class tends to teach nobody in particular.
The format works, when it works, because the clients see each other practising and quietly raise their own game. The format fails, when it fails, because attention drifts toward whoever is in front of the coach at any moment and the other two go quiet. Most of the craft of running small groups is in moving attention deliberately rather than letting it settle.
A small group is also a different commercial product, not just a cheaper version of the one-to-one. Clients are paying for the lesson and for the social texture of training alongside one or two others. Treating the group as its own thing, with its own design, is what justifies the price the coach charges for it.