I have minimal experience sending artwork to be printed professionally, so I am curious about something the printers told me- I laid out a multi page brochure with lots of text, photos, and charts. I used photoshop, because that's what I know. The bosses here kept tweaking the final version, after getting proofs back. After about the 5th time the printer was obviously slightly annoyed (though not rude or anything) and we were talking about how all these post proof changes were really running up the costs, but then he also mentioned that it would also be cheaper if I had used another format than photoshop (I was using photoshop PDFs), since Photoshop is not ideal for layouts like these, it was costing us more. I'm just curious, why would that be?
That's strange I've been in the printing industry for a while now, maybe because they don't have licences on all their computers with Photoshop and would have to use a different machine to print .psd files as opposed to another format your print place suggests.