I once encountered an intersection with a big "NO ENTRY" sign on the other side. I turned but google maps wouldn't give me another route, so I did a u-turn and came back to it from the side. Which meant I was close enough to read the small text underneath that said "vehicles under 10 tons excepted". I don't think I've ever been so angry at a road sign.
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.
By my work there is a nice clean sign at the main intersection that reads "NO RIGHT ON RED" with a separate smaller crusty looking sign below it that reads "4 to 5 PM" using a much smaller font. Of course the stark difference in signs means everyone just reads the shiny top sign and waits for the green at all times. I keep wanting to modify the sign to highlight the time.
