How to deal with the subject of masturbation?

So one of my daughters reached that age of discovering masturbation and started to do it everywhere which sent her mum crazy.
Her first reaction was to discipline her and tell her not to do it but I looked up advice on the various medical and parenting sites and found it was perfectly normal at that age so after we discussed it we introduced a rule that you can do that but only in the privacy of your own room.

She does it a lot, a few times every day I'd say but she's no longer doing it in public or around visitors so I think we've reached a healthy compromise. There are still the odd relapse so for instance a couple of months back she was upset and when I asked her what was wrong she said because her friend was there then she couldn't play with herself so I just said something like "well your friend has made an effort to visit and she'll be leaving in an hour and then you can go to your room and do that."

So I think that's a healthy solution since it isn't repressing those natural urges but it isn't something that should be just done in public. How do other parents deal with that difficult subject? Do you think this is the right opproach or should it be discouraged? I leave the difficult talks to my wife but I think this is really following the mainstream advice.