That depends on the skill and experience of the pro, and the dedication and " talent " of the student.
Its fair to say, that there are those in the pro/Am circuit are there for many different reasons.. but.. there are some very serious talented Amats.who cannot find a partner, but rather than bemoan the problem.. compete
I had the pleasure of coaching an amat couple a few yrs back, and the lady was an ex. amat. partner of Joe Jenkins. She was a past 3 times US Pro/Am. champ., and was a remarkable dancer.. the reason she stayed as an amat. was her profession ( Dr,in 2 sciences medical and research )
I have of course , known many others .