The first time I supported a round a/c I Si Bourne was also in support.
We had both done our rounds CW.
We were on leg 3, reached the top of the Bowfell rakes - which is basicallly spot on half way - We looked across the view ahead to the Langdales and beyond, Si and I then just instinctively looked at one another and said "easy ground from here !".
SO it does have its advantages.
Another aspect of why maybe fewer people go A/C may be that detailed data on A/C summit splits is less accurate - because there is less of it available. Perhaps people try a few legs and find they are way off some splits ?
The last time I supported A/C the contender was there on spec, I don't think he'd done any recce, the schedule was borrowed / cobbled together from various sources. I supported from Honister to Dunmail and within 2 summits I had concluded that the schedule was rubbish and I was providing estimates on what we should expect off the top of my head based on knowing the ground (I did pretty well too). ( He did complete by the way - that kind of guy - He did the same thing on the Ramsay, just joined in with some other guys on a whim and completed ).