The borders am matting - and general presentation - are as much of the "image" as anything else. The viewer's perception will be affected ... and, therefore, her/his emotional reaction.
I haven't been able to formulate any hard and fast rules .. sometimes a small print in a large mat "works" - fabulously; sometimes it just appears pretentious. Why? - I haven't a clue - that is why we have the idea of "aesthetics".
One thing appears to be universal ... most artists I've talked with seem to agree that "overpacking" - trying to exhibit too many works for a given space is - *very* irritating. It is better, by far to have too few, rather than too many. The "experiencers" must be given ample opportunity to give their attention to any specific, individual work. Overpacking shouts one message - insecurity about the quality of the work.
There is one outstanding web site - showing a number of gallery installations for *one* particular photographer: [
www.demarchelier.com ]. While *certainly* NOT to be taken to imply universal "rules" for everyone, it is still of interest.