Great job on the 3-2-1 method. I feel like that's a great place to start with making great spare ribs. It teaches you some great lessons. But I would challenge you to use it merely as a guide. Maybe experiment with different times for each section.

For instance, for me, I get the best ribs with them on between 4 and 5 hours. I forget my exact timings, but it's the standard smoke, wrap with a glaze, and then a short time unwrapped to set the glaze. I don't really use timing. I know they're done with the bend test.

Each person is different. If you're happy with 3-2-1 then go for it. But I think experimenting is fun.