From anna.aero:
"The science of route planning according to Ryanair’s COO Michael Cawley: “We don’t bother trying to analyse the living daylights out of a route, we have a look at the demographics, and then make a decision to do it – we accept that around 7-10% might not work but we don’t see this as failure – we see it as 90% success.”"
Interesting but not surprising!