You had me concerned for a moment. And looking back, that makes sense, but the the time of my posting, I hadn't had my coffee yet. As much as I hate that excuse, it's the truth.
The dealership I worked at had 2 techs (total of 8 of us) in on Saturday and was closed on Sunday. And that was a small dealership. The (huge) Honda shop across the street had 5 or so techs (out of about 20) on Saturday. I can't see a single disadvantage to having a few guys work the weekends for people who may not necessarily be able to make it in during the week.