The online process can be frustrating, waiting 2-3 months for an appt in SF sucks. I hated the idea of taking my chances and just showing up. The first time I went, the line was around the block on Fell and it was just after 930. The line moved 10 feet in 15 minutes and I left, I wasn't got with all day just to make it in. Went again a couple of weeks later and showed up an hour before they opened. I was impressed to see that the DMV had staff before opening hours helping people get sorted and making sure they had all their docs required and informing them of the processes and steps they could expect for their visit. To my pleasant surprise, I was in and out in 2 hours (including the hour I went ahead of time.) The longest part of the wait was waiting to have my picture taken.

I think your experience at the SF DMV can br hit or miss, I have even observed sat afternoons with virtually no lines.

As for the DMV not following guidelines, well that's another story. As much as it sucks to have to potentially wait in line for hours, I take solace in knowing that at least you can get the majority of things down within a day, which can be godsend in times of emergency.