Academics at Birmingham University polled senior managers from 20 councils and found that they felt ambiguous about the value for money offered by consultants.
But they were often used to make up for a lack of in-house skills to get a specific job done quickly.
Survey organiser Robert Dalziel said: ‘Managers’ experience reinforces the view that consultants are best used to complete routine, narrowly defined, managerial or technical projects effectively and efficiently.