Skimped on minor T2 items, there are a number of new gents toilets that have anything from 5 to 10 wash basins- but most have only 2 hand dryers. If you presume a need for x number of wash basins then there must be an optimum need for dryers. Minor stuff but it shows the mindset in play.
Can't say I keep detailed records, but isn't that the normal sort of ratio in public toilets?!?