A busy road I use to commute has been under construction for the better part of a year. Sometimes the lowered speed limit starts too far from the construction site or doesn’t end when it’s no longer needed. Drivers aren’t dumb and speed up when there’s no apparent need to drive slowly. Sprinkle enough redundant limits and people will question following them altogether.
Don’t create restrictions unless there’s an actual need to do so and when you do, make sure the reasons and benefits are clear to everyone. Every additional meter of a speed limit that’s no longer applicable devalues its power and respect.
You can enforce limits on people either by fear of punishment or by creating a reason to do so that benefits them. Which one do you think works better?