Yet the standard working week in the Netherlands is just 38 hours (per Wikipedia), and in Germany it could be argued that the economically most successful states have a catholic majority (although this shifted after WW2, for instance from Saxony (protestant) to Bavaria (catholic)). I think the idea of "Protestant work ethic" is mostly bullshit these days, and it's more about worker's rights.
The above creates a dynamic where people will still work 40h to hit breakpoints, or will drop down as much as possible to stay at their current breakpoint (because working more isn't getting them there anyway). Doubly so because income tends to be a far bigger decider for things like housing and rent (highest expenses) than budgeting.
However poverty and appearing to work hard to be at the top of an extremely competitive scramble out of poverty is my rough idea that isn't too hand-wavey in the direction of religion or culture.
And other SE Asian countries (poorer than Singapore) have more of a reputation of "work shy" cultures. If you can work enough so you're not starving and have a house and beer to drink, why work harder?
So clearly the link between poverty and a "work hard" culture is pretty weak.