I have supported people from several different hospitals, and I'd have to say there's an enormous variation in the care the CNSs give. My CNSs were brilliant at Luton & Dunstable Hospital in 2018, and they're still there, indeed one more of them plus an excellent support worker now. I still only ever hear glowing reports about them, and they seem to try to be present in all consultations from the point of diagnosis, so they know what the situation is first-hand with each patient. I saw them separately a couple of times too when I was first diagnosed.
I'm not going to mention other hospitals by name, but some simply don't have anywhere near enough. A CNS at a conference told me she only gets time to see each patient once, and that will either be at diagnosis, or at treatment choice - clearly, that's not good enough. Some hospitals don't have staff with the right personality doing the job - I've heard of appallingly insensitive nurses several times from a few hospitals.
I think one of the problems is that while we the patients can clearly see the value of CNSs, hospital management don't. If you've had a good experience with your CNSs, do make sure you feed that back, because in the current climate when there's a serious shortage of qualified CNSs, lots are due to retire soon, and hospitals are looking to cut back, they could so easily vanish.