What is the R.O.I. of fast decision-making?

Take this example from one of our client projects...

20 people x 5 hour off-site meeting x $125 unit cost per hour per person = $12,500.00 for one new product portfolio selection and prioritization "event"

This $12K meeting had no measurable result since none of the projects were ranked nor did they cull out the projects they would not fund. Basically these people sat in a room and presented unstructured slides to one another in an attempt to "sell" their ideas.

$12K was spent, not to mention the Opportunity Costs that were lost. What opportunities were missed while these 20 people were unavailable for 5 hours?

On the other hand, following this failed meeting we ran the same workshop which lasted 1-hour and cost our client (in people time) $2,500, or 80% less. And at the end of our meeting they had reached consensus, gained shared understanding, and had a ranked list of projects. Further, they had a FRAMEWORK for ongoing refinement as new data became available.

What service can you buy that gets twice the results while reducing cost by 80%.