The best book on the hows and whys and wherefores of therapy is The Misuse of Persons by Stanley J Coen. Because all that muddling IS misusing, isn't it? And therapy is the way out of the muddle.
Or read Harville? He has a book that describes 7 or 8 stages of development, says if you get injured at one, you kinda get stuck there. What you might be reading here (at least in my case; I ended up deleting my post about my T's photo because I freaked out after I read it and the SANE one after it) are postings from people who got psychically injured at stage zero, ie pre-oedipally, pre-verbally, which is why it's a big deal to ASK for a photo of our therapist - as infants, we never knew if someone was coming back, and that does something to your brain, but you don't really realize it now, you THINK it's just about the photo. But by working up the nerve to TALK to t about it, you start to trust, start to build good new brain wiring. Some t's call it "emotional muscle" - I told my t to STOP SAYING THAT because what does that sound like to you, or is it just me that has a dirty mind? Can we do a poll?
Anyway, I would say it helps, but it's like AA, it works if you work it. I AUTOMATICALLY say no to EVERYTHING my t says. He has to preface everything with a "this is just off the top of my head" or something like that, to get me to STOP AND LISTEN. I would like to know what personality quirk THAT is, that I'm doing, besides being a witch! If you don't do stuff like that, if you are able to hear and respond, you will get something from therapy.