I have experienced different scenarios at all the locations mentioned in the thread, even the popular ones mentioned:
The MA will say, go in the shower and I will join you in a minute. But she did not return for about 5 minutes when I am about finished. Then when she returned, she said, Oh, you are about finished, lets go to the table. I think the timing was planned.
Another scenario that has happened was-she would join in, but has no interaction, she would just stood there, stood away, soap herself, wait till I am done, then she would shower herself and get out. Showing totally no interest. Again this has happened at all the mentioned locations.
I think just having a shower may not mean anything-it is the individual provider that makes or breaks the fun of shower.