I find assessment to be the most fascinating part of the job. For what I thought was a very rigid, established, system, there is really a lot of room to very creative. Figuring out how students turn your word salad into their own knowledge is magical. I mused on what I look for in assessment a year ago. I still agree with the general idea: the grade part is irrelevant, I'm just curious to see what you think. I still have to assign grades in some thoughtful way, incorporating that continues to evolve.
Most of my assessment methods were driven by necessity. When I first implemented SBG a long time ago, it was driven by being more efficient with my time due to athletics. I needed assessments that were short and simple to grade. I also needed to reduce the amount of things I graded. Two years ago I dabbled with A/B/Not Yet for Calculus. Through the year I stopped reviewing student papers and had them self determine their level. Most of the self-ratings were pretty honest, in general I've found students are harder on themselves than you'd think. Last year, also due to athletic constraints, I put all of the determination on my Calculus students. I still had piles of Pre-Cal stuff to deal with an two sports consuming all my extra time, so that's just how it needed to be.
In retrospect, it was a swing too far in the "grade how you feel" direction. I have since retired from my major athletics duties, and now have the time to give students a greater amount of attention. You might frown at slacking in this area, and believe me I wasn't happy about it, but to you I gently say ask a coach what the grind is like.
Here's how I handle assessment in my three subjects:
I use a stock SBG (0-4 scale with two required attempts) system here. It's something I know, and the multiple attempts play great for this audience. Kids are encouraged to keep their resources (notebook) organized by using them on the assessment. Kids can also work on them together. Multiple versions are scattered around. The sections are short and sweet: demonstrate a skill and explain it to me. All of the kids in this class are very capable, some require more time than others. To discourage "speed = smart" I keep the problem load low and make them do a lot of explanations.
My intent with this class is to dedicate their time to classwork as much as possible. The classes are small enough (18 and 15) that some intense differentiation is feasible and probably best. I don't have a plan for that yet. Assessments are just a piece of classwork I happen to look at and shouldn't be feared. A post-secondary goal for these kids is increasing the number that can qualify for college level math courses. Though this class is College Algebra in name, it does not award any credit (since I lack a master's degree I'm obviously unqualified to grant credit, apparently).
I am keeping some of the ideas from my A/B/Not Yet experiment, namely the self-determination aspects. Assessments are short (half piece of paper) and sweet, with a combination of skills and explanations. There's a max of 10 questions and each assessment is rated on a 0-10 scale. Though 1 question does not necessarily equal 1 point. Students have about 35 minutes to complete the assessment. When I call time they grab a marker and I show the answer keys. Students give themselves as much feedback as they desire. Though unlike my previous system, I collect the papers and assign the rating. I take a holistic view of the paper when determining the score. I put a sticker on there if they get an 8, 9, or 10. The kids making a pre-check helps the rating process go faster.
Right now things are still pretty introductory, we don't know enough to tackle legit AP stuff. Eventually we will transition to AP-style problems on these. They will still take benchmarks to help them make an informed decision about the AP Exam. I expect about 60-70% (~50 out of 75) of these kids to opt-in to the exam.
It's a small class (16) and a group of kids who put enough pressure on themselves without me being hardcore about tests. Their assessment system is divided into open book (35% of the grade) and closed book (45% of the grade) activities. In all cases they may collaborate on the task at hand. Open book assignments are chopped into a few sections worth a varying amount of points a piece (anywhere from 2 to 9) based on length or complexity. Each section is its own gradebook entry. Because of the speed required, we have already dabbled with legit AP material, so often I use the open book questions to give them a shot at FRQ style situations. The goal is to be diligent about how to make a math argument.
Closed book assessment has been done via Desmos Activity Builder. Topics vary and are usually conceptually in nature. Though the College Board is stuck in the stone ages with calculator technology, I use these as an opportunity to get them better at typing math notation, among other things. Use of Activity Builder spawns from a comment last year that students were fine with all the writing, but typing might be more preferable. These activities are about 15 slides long and I use the dashboard to assess how they rate on a 0-15 scale.
As this group transitions towards even more AP material, closed book will become a little more intense. These students will also take benchmarks to give them an idea about how they'll do on the AP Exam. I would be wildly surprised if the opt-in rate for the Exam was under 100% here.
Assessment can be whatever you want. Find a system you like. Experiment with one you're not sure about. You can always make changes. I don't love points systems, but if you don't want to work within 0-100, don't. There are many many ways to see what kids know and don't know.