You bring up a really good point!  Which is that even among expert injectors, there are some differences in technique. As long as you are getting an excellent result, and she's observing all the safety precautions, then small variations in injection technique aren't important. 

Personally, I can get good placement without doing that and I think it may make the experience less comfortable.  If you are reasonably comfortable and getting good results, your doctor's way sounds fine!  Dr. I