Integrating the sub(s) into the whole system is something completely different than finding a location for the sub to perform at its acoustic best. I would argue that you should do both with proper integration being an absolute must.
In my experience, I located two spots where subs performed well, I placed the subs in those locations, then proceeded to fine tune; integrate. I did move one of my Subs slightly after setting them in their original places.
Results were quite satisfactory.