We had this bespoke illustration designed for us by Jake Goretzki last year. It nicely sums up what tends to happen in many an innovation workshop:

For too many agencies, the metric for a successful day spent generating ideas is quantity. Lots of ideas means more for the money. Quantity equals value. Or does it? In fact, it’s a false economy. Mammoth thought-lists will quickly be whittled down, so it makes sense to skip the disappointment and focus on a small number of big ideas.
Our view is that by combining the power of design with speed, strategic creativity and collaboration you well and truly end this thinking.