The applications are almost endless and what would be “most useful” really comes down to what is most useful for the business you are in. In general terms, facilitation is very useful when you want to get input and involvement in:

Finding the cause of a problem or difficulty
Making a decision
Creating a plan
Clarifying an emerging situation or issue
To provide a more specific example, I have spent a great deal of time facilitating risk assessments which includes elements of both decisions and plans. The majority of that work has been in aviation where the complexity requires the involvement of people from a range of functions and disciplines, and the reduction in incidents and accidents has an impact on both health and safety, and the bottom line.

In many ways, it is easier to say when facilitation is not useful and that means anytime when you are not interested in engaging with people or gathering their opinions.

For example, if management is making top-down decisions, which is sometimes entirely appropriate, then that does not require a facilitator. In fact trying to use a facilitator in that situation almost inevitably leads to failure. Where things go off the rails is if there is a difference in expectations e.g. a facilitated group thinks they are making the decision, or at least providing input, and it turns out the decision is a done deal and Management is simply trying to get people on board.

That doesn’t mean there might not be a role for a facilitator in that, but clarity of expectations and roles is critical. It works just fine for Management to say “Here is our decision”, and to organize a facilitated session on how to best implement that decision.