I came across one in Italy that was meant to prevent you from using a street during school days from X to Y am, and Z to W pm, except on weekends, bank holidays and school holidays.
The idea is well-intentioned, but implementing it by making drivers try to parse arbitrarily complex conditionals while driving is unwise.
There's a sign near my house for a school zone with a reduced speed limit, that used to have conditions similar to the GP's example (though not quite as bad) But they recently attached a yellow light to the top of the sign and changed the condition to "when flashing." That's a much more effective solution.
