My father was raised Protestant, I went to a Protestant elementary school and was raised half secular, half Protestant and I generally recognize it very much in myself, my father and quite a few people in our surroundings (mixed religion area.)
The thing is that it's not necessarily so much about working hours here. It's the general feeling that every moment should be intentful, purposeful and, like our churches, generally without frills.
In a way it feels less like 'work hard' and more like 'don't endulge yourself' to me.
'Protestant work ethic' is something I've only heard talked about in America, usually couched in the form of an indirect put-down of non-protestants. Northern Europeans are more likely to view predominantly Catholic countries like France, Spain, Italy as stereotypically lazy, but this is usually ascribed to the Mediterranean climate.