I only tell if it seems relevant to something that I need to say, or I would tell if she asked. I figure that if she doesn't ask, she probably doesn't want to know about it each and every time. Why bombard her with stuff, when I'm giving her plenty to deal with as it is? And if it doesn't matter to me, then why should I think it would matter to her or anyone else either?

But for someone who feels guilty about keeping it a secret, I would say to tell, so that you don't have to carry that guilt around. Or also if you don't SI often, and it's significant when you do, then that would be important and you should tell.

So, I think you should tell if it helps you to tell, whether directly (because you feel better if you are not hiding something from your T, etc.), or if it's important and your T needs to be aware of it so that s/he can help you better.

BTW, I'm not keeping a secret by not telling her every time I cut, since I have given her an idea of what I do and the frequency - I just don't think that she needs a news update every time it happens in my case.