Whooaa.. wait something is not right here. I do real estate photography for multi-million $ homes in California and I seldom have to do more than 3 shots. 90% of the time, I do 3 shots - +1ev, 0ev, -1 ev. Occasionally, I have to do 5. The whole point of using bracketed shots and HDR is you DON'T have to care about what is over and what is under. You set your 0ev shot to be what the light meter reads and then you do one over and one under and voila.. that's it.
Here are
architecture HDR shots - all done with 3 shot bracketed HDR (that don't look like HDR!)
Here's my
brother-in-laws work with 2-shot HDR (using Enfuse plug-in for Lightroom). I don't know that much about the Sony a7r for bracketing or HDR work, but if you have to do more than 5 shots, there's definitely something wrong with the setup.