When I started at Lincoln High School in 1970, there were SO MANY students enrolled that the school had to adopt a 9 period day where you would attend periods 1 - 7, 2 - 8, or 3 - 9. So there were 3 lunch periods each day.
Lincoln Market on the SW corner of 21st Ave & Quintara was a favorite place to get lunch and you would enter into the butcher shop entrance on Quintara to get your sandwich or whatever and walk through the store streamlined to the front where the cash register was. They were so busy that they didn't even take time to put the dollar bills into the register, but would just drop them into a box on the floor and then make your change from the open register drawer. I think the store was owned/run by two brothers or cousins who I remember as Ray and Alex (again OLD memories MAY fail here too). It wasn't particularly the best food in town, but a heckofalot better than the cafeteria...and you could smoke in the store while waiting in line too. Hahaha