Go one-on-one if you want privacy, focused guidance, and a pace set entirely by you. This suits people who feel overwhelmed in groups or want space for sensitive, personal work.
Choose a small private group with people you know if you value trust and shared support. Pick an open group if you want community and a lower per-person cost, understanding that attention is shared and group energy can be more intense.
Whatever you choose, prioritize a skilled facilitator, clear intentions, a group size that feels right, and time for preparation and integration. For an overview of formats and what to expect, see this introduction to truffle therapy. Also check local laws and practical logistics before you commit.
Pick the setting that best fits your goals and comfort today.