Nope. There are many rural roads where 60 mph would be inappropriate but the national speed limit applies.
IMO, it shouldn't.
Those rural roads should have appropriate limits set.
IU think it is utterly bonkers when you are driving along a nice, open and wide A or B road which has a 50 limit for whatever reason, but turn off onto a tiny lane, the limit immediately becomes 60.
That is just laziness on the part of traffic planners and regulators.
There are many villages where the limit should not be 40 mph. Plus remember is an absolute limit after which you are breaking the law. You should not see it as a target. Many treat it as a minimum.
I never see it as a target. But if that is the limit, then there should not be deliberate measures taken to cause you problems if you drive at that speed.
If the authorities think that 20mph is the maximum appropriate speed for a road, then they should set the limit to 20, not set it to 30 then put in speed bumps that can't be taken at more than 20.