I've got a book posted that is on its second "hold" waiting to see if the member has the credits. It's a fairly popular book with more than 200 members "wishing" it. I'm sure it'll get picked up soon and I'm not in a huge hurry for the credit but am curious: What happens if the same book gets entered right after mine? Does it go back around to that first person who ignored (or didn't have the credits) to claim it? I've sometimes wondered if this is the reason you will see "wishes granted" seem to stall on a popular book and then suddenly a whole bunch of wishes are granted. 

I'm pretty sure that if someone doesn't "claim" a book, it gets taken off their wish list.  Unless they have it on hold or there is a requestors condition or something like that. 

That new button "not now" that is an option on your WL books can be used only once-- the book skips you in the WL line when you do that. But if another copy is posted right away and gets offered to the skipped wisher, my understanding is that  they must accept that copy or it comes off their wishlist.

For that reason I always keep at least 10 credits in reserve in case I get WL book offers. Also the reason I didn't use the WL benefit the first full year I was a member--- I never had any credits as I'd always spend them as soon as I got them! 

If the "Not Now" button is used, the request is immediately offered to the next member on the wishlist.  As long as the member has the book on 'not now hold' another copy will not be offered to them, and this option can only be used once per book.  If the member takes it off 'not now hold' it will not be available next time the book is offered to them...the only option at that time would be to accept (for a credit) or decline (removing them from the wishlist).

If the requesting member declines or lets the request time out, the book is removed from their wishlist.  If they want to add their name back on the wishlist, they must start over at the end of the FIFO list.

I look to see if the book rolled over during the day or in the middle of the night.  PBS is set up to roll over in the wee hours.  A daytime roll over would be the decline or not now button.

The not now button places the book on Hold.  Not responding removes the book from your wish list, losing your place in line.

It's pretty common for a book with a long WL line to have a pile up of inactives at the top. Same with heavily posted books.  People lose interest in PBS and can pile up at the top because a lot of active users post or order direct from other memers instead of FIFO and they know to put their account on vacation or WL books on individual hold if they won't be around.

I've sometimes wondered if this is the reason you will see "wishes granted" seem to stall on a popular book and then suddenly a whole bunch of wishes are granted.

In my observation, the "wishes granted" shows timed out requests, rejected requests, as well as wishes that are actually "granted".  I've even seen it count me as a "granted" wish when I've been offered a book, I've accepted, and then the sender declined because of my RC.  So it's not always a good indication of how many people are actually receiving that WL book.