"Yes, this is done. I have read about it in the past, i believe it was the late steroid guru Dan Duchaine that wrote about. Basically anyone that could afford it could get all their receptors mapped and he could figure out which compounds and doses would be the best for you based on that mapping, body type, blood type etc.."
There is no "receptor mapping" that is done for this purpose. I can't even think of what this would do. All steroids work through the androgen receptor, which is known to work on a dose response curve, essentially the greater the dose the stronger the response, until a given max is reached.
Blood type has nothing to do with steroidal effects either, so this is a non-issue.
Arnold's physique is a combination of genetics, drugs and hard-work.