You must be referring to basic vector work correct? Even at that, with approvals and revisions going on, 24 hrs is tight for anyone but their are some.
I think I've heard of a Co actually named 24hrArtwork. Might try that. I think they are overseas tho but should not matter. I also don't know if they actually prepare it for print as well. Most 24 hr services are just "creating art". Making it production ready adds more time to a job. Some jobs take me 30 min here, but then separating it adds and other 30 min. Sometimes an hr when I get fancy and all of our work is stupid simple vector.
Let me add that (this time is including approvals/emails/phone calls).