Include those if you must (although the number of vehicles joining the Motorway from them can probably be counted on the thumbs of one hand - i.e. they are irrelevant). There are still a lot more cameras than there are on-slips.
the maoster:
Dunno how true it is but I was told that the cameras are linked in pairs but not necessarily in numeric order, so for example you may have 5 sets but the links go; 1&3,2&4,3&5… Like I say this is what I was told.
They used to operate in fixed pairs - not because they had to, but because that’s the way they were approved to operate. They have been fully networked (within a given set of roadworks etc) for several years now, so your average speed between any two cameras can be calculated and used for enforcement purposes.
Silly question, I know but with all this effort going into working out how to fool them, why not just stick to the posted limit?