The thing is, when we started talking to Hurtwood Control years ago about maintaining trails on their land - stuff like BKB and Yoghurt Pots - we were also talking to Surrey County Council and the Surrey Hills AONB about trail usage, and catering to mountain bikers.
Their solution was to get the highways and GIS peeps to look at installing traffic counters on trees to measure usage of trails like Summer Lightning and BKB.
A lot of this was done from the point of view of catering to a quite large group of people who brought quite a lot of cash to the area - while also getting an understanding of the scope of the 'problem' that some local residents saw. At no point was it about defining the bicycle menace or anything like that.
Apps like Strava solve a lot of the problems that landowner groups had up until very recently - understanding where mountain bikers rode, and in what numbers. Strava et cetera means a huge cost saving - rather than getting out there with a GPS and trying to find stuff, it's a case of a bit of desk research, instead.
Taking a quick look, I can see that a segment of BKB was ridden 14,603 times By 2,558 people - proving that it's a popular trail (Summer Lightning, in comparison, is getting a light pasting - about 4,000 odd rides). I remember someone doing a count of the number of riders that passed us on a BKB dig day years ago, and extrapolating a number in the hundreds on a warm weekend day.
The outlier numbers (Fastest and slowest) aren't as much interest as the mean or average speed, I'd say. There will always be people who race or ride irresponsibly, regardless of the vehicle they use - it's about proving that a trail is a well-used resource, not whether it'll get the Daily Mail brigade frothing at the clopper, that bothers the local authorities.