Pushing the schedule that hard seems like a good way to ensure mistakes. I'm not sure I'd be willing to work that way with any of the stuff I do. There are always rush jobs, but not at the expense of quality either for that job or the ones it's putting off till later.
From the APS
http://stamps.org/DisplayPage.aspx?id=197
"12.No item will be accepted if the owner insists upon a deadline date for its return. Owners should allow 90 days before expecting a certificate. Since items are submitted to expert committee members for their opinions by mail, unavoidable delays are often experienced."
Of course their guarantee is a bit better. Not much for very high end stuff, but great for most items.
http://stamps.org/APEX-Guarantee
The certs are atually meaningful, and it's only $8 if they decline to make a decision. Most items get through the system reasonably quickly, but some really special ones can take a while. And controversial ones can take years and still get what's essentially a no decision. One batch of questionable Hawaiian stamps literally took years, and involved actual experts in printing, paper, inks, and probably a few specialties I didn't hear about. The English equivalent to the APS took it on, and ended up writing a book. And they're still controversial, although most likely fake. I've seen them in person, and they're spectacular fakes -assuming they're not actually real.
If you've got time there's lots of info here. delay in certs? These have only been waiting since 1919.....
http://www.hawaiianstamps.com/mi_grinnell.html
Steve B