How much transparancy?

I usually have little to nothing to hide and especially in business. But the reality is that there are times that you cannot give the complete picture. Maybe it is relevant to an acquisition or pay or even things having to do with HIPPA. However more than not I see others hide things or treat them like they are top secret? Why? I am guessing that many times I give up too much. What I think about a process, how others have treated people or even mistakes I have made. But sharing any of these can help us grow together? I should probably focus more on sharing my mistakes since they are mine to share. The other part of this is when you cannot share it can make others super uneasy and possibly damage trust. The easiest way of overcoming this is saying that it doesn’t have to do with the person you are speaking with (Assuming it doesn’t…Don’t lie) That is what most people want to know. For now I will try and stay on the side of clarity without giving away anything that shouldn’t be shared.