I just dropped off some documents at SSA in SF. Most people in line didn't have appointments. I already know how frustrated they'll be (been there, done that).
If you want fast service make an appointment. Trust me. It's a 4 hour wait otherwise if you get seen at all. Appointments will be seen first before walk ins.
What is more frustrating is that the appointment system favors people who 1) have the luxury of time to go through the steps of to make an appointment, 2) have even more luxury to take time off work to go to the appointment that may be as much as a month later, 3) know how US government systems work, and 4) have access to Internet/computer and a mailing address.
There are so many people who, if they lack even one of those things, will be at a disadvantage.
charlobo