For me, and for the client companies I can influence, the answer to the agenda question depends on the formality of the meeting and the number of issues to be discussed and addressed. If a meeting is very informal, brief, and focused on a single issue or very limited set of issues, the agenda might be verbalized (or assumed, based on history) rather than written. So, a shift-change meeting in a factory setting would typically not have a formal, written agenda, as the off-going shift always briefly updates the on-coming shift, following an agreed-upon pattern that need not be verbalized again and again. Nor would an after-action review for a first responder group require an agenda, once all members of the team are familiar with the usual structure the team follows. A meeting with a student to advise on course registration or to make a course schedule adjustment would also not have a written agenda – a simple “so we are going to get you in the right level of French class” would do. But for longer, multi-issue meetings such as regularly occurring staff meetings, or project team meetings, a written agenda, circulated in advance would be in order. I would say, when in doubt, tilt towards more rather than less structuring of a given meeting.
I could envision some very special circumstances in which an “agenda-free” meeting might be in order, say for very open, unstructured, creative, brainstorming meetings. I think that for most of us, such a circumstance would be rare.
I have not had clients or colleagues balk at using an agenda… but they know I take an organized and structured approach to my/our work… it’s how I am wired… so maybe they are just humoring me… ;–)