How do I know if it's enough?

I think it would be worth finding someone with a good overview of the topic and seeing if they think you have it covered.

If they won't want to give you a lot of time or you don't want to share the whole thing you could just ask them to look at the table of contents and synopsis--any major omissions should be apparent from that?

Before you get an overview, have you made sure you have exhausted all research? Have you any questions in your head tweeking at you on an area that may need more? Have you said all you can say? Does the book, when editing, cover everything there is to cover? Are you happy with what you have?

If so, yes, you have enough.

Yeah, I can't add much more than what the other posters have said. My first book was like what you're describing. I was writing the comprehensive book on the subject and didn't want to leave anything out. As I kept researching and interviewing people, I just kept adding things and adding and adding until there wasn't anything left to add.

I did have at least two experts read the second draft, and they provided a lot of good feedback, so that was a big help. Much later, after acceptance, I was still finding new things to put in. And now, four years later, I've uncovered more tidbits that also could go in, but now it's kind of too late. Any information I find now just is not that critical.

I guess what I'm trying to say is that there will always be stones left unturned, but just try to find as many as you can while you're still writing the first drafts.

And if your chosen publisher wants the manuscript after it's finished, then you'll have to finish it, obviously. But there's no guarantee that they'll accept it. OTOH, you could write a proposal and send it out to other publishers before you finish, but then that just takes time away from finishing whatever draft you're on now.

allen

Hi Greenwolf,

My take would be to publish it right away.
I don't think there's ever a chance that you can cover literally everything.

In anycase, it'll be reasons to publish 2nd edition, 3rd edition, etc.
Just my two cents.

Cheers,
TOFUmonkey