I would suggest rethinking this requirement. In my mind it can be construed as ‘must have experience building an app sub-optimally in regards to WUs’…there should be some other metric to use that determines if the developer has had experience building an app that gets a lot of usage. But, also keep in mind, a great developer may have built tons of great apps for businesses that fail to launch or gain traction, which can have nothing to do with the developer.
Maybe changing the requirement to ‘must have experience reducing workload units by X% on other applications’
You might have similar success as the quote above with just an hour or two on a training session…the quoted user scheduled a one hour session with me to get those results.