I don't know if you are working in a system like prinergy/preps and are located in a situation where the presses are, or if you are doing digital print. In Prinergy workshop for example, when chucking the files
into the imposition with their offsets, I used to work out the percentage of how much bigger the files have to grow, then set in the correct page size, workout the new offset figure, and then vps the whole thing to see how it looked - then send it off to the client for approval. That way I did not have to actually touch the files. Otherwise I was responsible for any mess up if I touched them. It just makes things, say a few percents bigger, and sometimes the client is happy with that. I have not worked with any of the other progs like Apogee having been at the same place for the last 15 years, so I can't say if the same thing would work. But it used to save me a whole heap of time and hair pulling-out.
Pitstop - the greatest editing tool I ever came across