Well, I don't know if I'm doing an official "SBG" thing, but this stuff I'm doing now is finally starting to work for me.
Here's what I'm doing (chronologically): On the test/quiz (the only difference to me is that tests reach back a bit further and are more comprehensive) I list the topics that each question covers. Students take the test/quiz. I grade each question individually (2/2 for #1, 4/6 for #2, etc. depending on the number of parts that each question has or level of difficulty) and then combine skills in the gradebook (so, if questions 1 and 2 are the same in the previous parenthetical, then that student would have a 6/8 for skill 1). I write feedback where appropriate and return to the students. So far, I have been able to return the assessments within a day or two.
Students then have a few minutes to talk with their group (of up to 4--so far, student chosen) about what they missed and how to correct their mistakes for the future. Before today, I would have them mention to me when they would like to come back to retest or requiz over certain questions and I'd stay with them after or before school. Well, due to outside-of-school-circumstances, my wife and I were a one-car-family for a couple weeks and I had to run out before it was convenient for many of the students. So, today I've implemented a slightly new system.
I have a sign-up sheet in the back of the room with columns for Student Name, Test/Quiz to Retake, Topic(s) and Question Number(s), and Date to Retake. Students may go back there at any time and sign up to retake questions within the topic (in the above example, again, I would make them redo both questions 1 and 2). I grab the list at the end of the day and write any appropriate questions for the individuals on the list.
Our school has a room called "the learning lab" (LL) where teachers can drop off materials and students can go during their study hall to make-up any missed work. Since almost every student has a study hall at our school, it is most convenient for them (and me) to have them go to the LL to take their retest/requiz. They are also allowed to come in before or after school to my room to make up the test or go over any content questions they have (and now that we are back to having individual transport, I don't have to stress about my wife waiting for me to come get her).
This is week 4 of the new year and students still seem to be getting a feel for the kinds of questions I ask and the level of understanding I expect from them (much more difficult and and much deeper than they are used to, it seems).
Many still get their tests back and struggle with the idea of, "Is a 7/8 worth it to keep on this topic or should I come back in and retest?" When asked directly, though, I tell them, "You should always come in and retest. If you got a 7/8 the first time, you pretty much get it, so it'll be easy to run through those the next time and you can get that one part you missed right and you'll have a 100 in here." Win-win-win. Generally they seem to agree with me and probably have in the back of their mind that even if a stupid mistake comes out the 2nd time, they'll have a third time to come back as well.
At the moment I'm limiting it to 2 retests because I don't want them to come in every day and just hope they get an easy question that they get by luck (and also because our online gradebook "Gradespeed" has only 2 spots for retakes). As they're getting used to the system, I'm sure a lot of them would try something like that. Two retakes gives them an option to realize that they didn't just forget the negative, but missed the entire concept and focus to come in a third time and get it right.
At first it was a bit of a hassle trying to accommodate students on-the-spot by either writing out a second quiz and just telling them to do the ones they wanted or making up questions while they stood there (they were impressed by that, and I don't mind doing it, but when there's a line of students, it takes a bit to write them all down). With the sign-up sheet, though, I feel much better about taking my time to write out individualized retests for the student requests and bring them in the following morning for the LL to file away until the student shows up.
So, I'm starting to get excited about the method. I don't think students are quite at the point of being "excited" yet, but they do seem to appreciate the lower pressure. Parents certainly seem to appreciate it as well since they can keep up with student grades online and see what topics their kid needs to work on and stay on their backs about coming in to retest.