I truly enjoy apartment shops, they are my favorites. I can knock out 3 a day, no problem. I do them for four different companies.
My on-site visits average about 30-40 minutes total. It's usually 10-15 minutes in the leasing agent office going over the basics of your needs/wants.
Be prepared to have some general needs: one or two bedrooms, upstairs/downstairs, by the pool, covered garage space.
Then there's a 10 minute tour of either a vacant apartment or a model apartment. This is fun for me; I like opening the closets, asking questions about BBQ grills, peering over to balcony to comment on the view.
Often you need to make an "objection" - one that the leasing agent can overcome. Think about it in advance. I usually worry that my furniture in a specific room won't fit.
Finally, there's a 10-15 minute "close" once you're back in the leasing agent's office. You shouldn't get a hard sell - but you should listen carefully to the leasing agent's closing and be ready to ask your Fair Housing question. Read your report beforehand - that will help a lot to understand the different types of closing.
My apartment reports take me about 45 minutes to write. They used to take over an hour when I first started. I try hard to write good narrative for all the sections.
Good luck!