This is up to each individual client. Some clients may live far away and it would not be feasible to be present. Some would prefer to leave the inspecting to the inspector and read the report later. Some like to be present for every minute and ask questions along the way. Some like to be present right after the inspection and have a walk thru of the home to go over any issues found or other points of interest.
As a home inspector, I have encountered all of these clients. I allow each client to choose their level of participation in the inspection.