Hi Twitch, although I do not have personal experience of cutting when I volunteered for a charity which supported young carers a few years ago they provided counselling.

I was told that at that time the current thinking was that people should be given clean blades (similar to how drug addicts are given clean needles) and ensured they knew safe techniques to cut (as you describe). So the focus was on safety but there was recognition that the cutting was a 'safety valve' in that in itself it helped a client avoid more harmful behaviour towards themselves.

At the same time the focus in counselling was about addressing the underlying issues which led to the cutting, rather than the cutting itself.

This was around 5 years ago and was in the UK. Things may vary in other countries.