One of the latest statements of Matt Cutts related to last Panda and Penguine updates along with new
search algorithm Hummingbird ( little bit of interesting reading ) was that that the most important thing is content.
Good backlink background and site availability are second or third now and who knows what else.
Answering your question, if you "mentor" showed you good way of doing the money in this business and told you to not overuse same template on your sites on your server on few of your ip's then I would listened him. Better be on the safe side.
But then again I bet that there are hundredths of sites using same template and some of them are doing great while some of them not so much. There to many factors to be taken under the glass and I read somewhere that when Google indexes the site, it takes over 1200 factors about the site; server, content, backlinks etc etc and I bet that design also play a role there. Who knows
