You can mostly second guess the issues, although lawyers are there to add the experience (case law) to what you may already know. Some of it is surprising and that's what can wrong foot the amateur.
I would never advocate not having a lawyer, but as I say thinking about what could already be a point of dispute is already ahead of the issue.
It's the only one you'll need - it basically covers everything required to jump into an intelligent conversation with your attorney.
There's quite a continuum between studying as much as a lawyer-in-training, and going and taking a "Business Law 101" course, or just reading the textbook from a "Business Law 101" course. I think most entrepreneurs would be well served by at least reading over such a textbook or taking such a class.
Large companies operate on the "what we can get away with" principle, which of you put it in the context of this forum is a Law hack.
For example earlier today the telephone company O2 in the UK was lambasted for including people's telephone number in the header of all http requests of every site visited on a mobile device. Someone somewhere made that decision not knowing it was illegal, perhaps not even stopping to think about it. Or alternatively they made the decision in full knowledge that it was illegal, but so obscure that Joe Public would probably not find it or understand the implications even if they did discover it.