As I've progressed through the game, I've been steadily gaining Insight via fighting bosses and Madman's Knowledge items. Ultimately, I'm interested in seeing what I can buy with Insight from the Insight shop in the Hunter's Dream, but I haven't gained access to it quite yet, so for the moment I have a decently-sized Insight pool just sitting on my character.
Unlike Humanity in Dark Souls, I don't seem to lose any Insight when I die in Bloodborne, which is nice, but I still feel a little nervous about having an active Insight count on the HUD, as though it might be possible to lose them somehow, such as through PvP or something like that. I know that you can spend Insight to summon other players for co-op play, but I'm only concerned about whether it can be "taken" or "lost" somehow.
Do I have anything to worry about, or can I consider my Insight to be safely "banked" until I'm ready to use it?
If my Insight is safe, is there any reason not to immediately use all future Madman's Knowledge items when I obtain them, rather than keep them in item form until they're needed?