Once upon a time, a friend passed on what I consider some absolutely fantastic writing advice: "Writing should be like a miniskirt: Long enough to cover everything; short enough to be interesting."
A lot of agents mention on their blog what would be about the right length for a book, depending on genre and intended audience. I have heard agents say that after certain word counts, they just put down the query, because they know the book doesn't have a teardrop's chance on a hot stove.
There's some disagreement on the particulars, but basically any agent will tell you that the key is not to waste any of your words. Basically, if you're writing an 93k YA novel, then those 93k better be worth getting through. How do you think J.K. Rowling got away with writing 160k words books? Because people kept on reading them. People thought the words were worth it. At least, worth it enough to keep reading.
Every word should be covering something that needs to be covered. It should not be there covering things that are best left uncovered. This would be one of those areas where underwriting comes in handy. Saying less to mean more (something that I can admit I don't do perfectly. Yet.) is a great way to tighten up your prose and create subtle works.
I'll admit it, when I write out my first drafts, they tend to meander a bit. Sometimes I get a little lost. Sometimes I come up with something I think is a brilliant ideas but end up abandoning or something that just goes nowhere. That's why I edit. I go back and remove the words that aren't contributing to my plots. I go back and remove the words that aren't contributing to my characterization. I go back and remove the words that aren't contributing.
Basically: Long enough to cover what I want to cover. Short enough to be interesting.
What's your policy on text, length, and editing?