Upon applying to potential internship sites through the Washington Academic Internship Program three things are very clear: 1) interns work, at mininum, 32 hours per week, 2) Fridays are reserved for seminar and 3) interns must work on Saturdays.
Oh, wait. That last tid bit is reserved solely for my internship. How nice.

Jokes aside, I've enjoyed working on Saturday afternoons. Although working on the weekends is not a requirement, per se, it is "highly encouraged". At first I was a bit peeved, thinking, "I'm not even getting paid and now I have to give up my weekends, too?" But I quickly realized that working for a couple of hours on weekends is a great way to earn comp time, either to be cashed in for a full day off of work or spread evenly Monday-Thursday, leaving work an hour early each day.

I work for a museum and, like almost all museums, its busiest times are on the weekends when families spend time together or individuals have free time to stop in for a quick visit. For the museum in which I work, visitor studies are extremely important. The data we collect, through surveys or interviews, allows museum directors and curators to understand why people come to museums, visitor demographics, etc. Obviously, this information must be obtained during the museum's busiest hours, so as to increase our response rates and obtain as much data as we can.

In fact, if I didn't have to work on Saturday mornings I would most likely sleep in and miss out on fun museum activities. So, if your internship site ever "highly encourages" you to work on a weekend, do it. It's fun and you'll learn something in the process. If I had passed up the opportunity to work at a fesetival two weeks ago I wouldn't have been able to pet these llamas:

Carolyn Behmer