That's a good question and it doesn't always have a standard answer. As you point out, different doctors do things different ways, however, most procedures have standard protocols that should be followed in order to achieve the best possible outcome. So, if Dr. Smith and Dr. Jones both perform the same hip replacement, using the same technique and the same hardware, in patients who are similar in age, health, weight, and lifestyle, their rehabilitation protocols should be very similar.
However, things can change drastically with any difference between the patients, techniques, and hardware used. If Dr. Smith uses a partial replacement approach over Dr. Jones' full replacement, their recommendations will be different, as they would be if Dr. Smith did to different procedures on the same day.
Researchers are constantly trying to find the best way to do things and the best approaches to take so treatment plans are changing and evolving. What may have been not recommended a few years ago, may be standard procedure now.
Hakan Strom, MD, et al. The Effect of Early Weight Bearing on Migration Pattern of the Uncemented CLS Stem in Total Hip Arthroplasty. In The Journal of Arthroplasty. December 2007. Vol. 22. No. 8. Pp. 1122-1129.'