My shop is a mix of ready to ship (20%) and made to order (80%), so that people can find what they are wanting quickly, I keep everything organized by style, not by ship time. I find people do not mind waiting for shipping. I keep it like this January through October.
November & December, because of the holidays, I do move all the ready to ship items into their own "Ready to Ship" section. I have no idea if this has been beneficial or not, haven't taken the time to really see.
I also think a lot of it would depend on how many items you would have in the "Ready to Ship" section. Something that can be quickly glanced through, 20-40 items. Chances are someone looking for something to ship now, doesn't have time to wade through 300+ listings. So if it's short, they don't find what they want, they can still checkout the rest of your shop sections to see if there is something they like.