The range of techniques is considerable. Each has certain advantages and disadvantages and is better for some circumstances than others. Consultation documents, Media coverage, Exhibitions, Public Meetings, Question and Answer sessions. Interactive web-sites, citizens' juries, visioning exercises, various forums. The final choice of method will depend on a whole range of factors once purpose is clarified.
Some techniques are better suited to large groups, others are more targeted.
Some require more human resources and financial input than others. Some sit more comfortably with the culture and approach of a particular authority than others. It would be unwise to prescribe techniques for particular purposes. The judgement about fitness for purpose has to be made in the light of each case. The challenge is to establish a procedure so that fitness for purpose can be determined, reflecting the various objectives of the authority.