No need to get anxious...but I've done the 6 house where they've offered us the option of 60min or 30min and the group has voted 30. I just ran to Annie's Pretzles worried about time, but they gave the 30min, then walked around BSing with each group/table and asking for feedback for another 10min, and then gave it "a few more minutes" for everybody else to get back. Unless you're waaaaay over the time limit, they aren't going to leave without you...and if they do, I believe someone from BMG looks you up and radios your tour guide so they can get you caught back up ad I think I've seen people do that.
If you do any kind of fast service, including going in park, you should have plenty of time and can bring it back to BMG and eat there. They aren't going to make you cut your meal short.
But you're likely not going to be able to go to Hard Rock and have a sit down meal (which I've done in the past and we had to repeatedly ask the bartender - ate at the bar - to get back in time).