Actually doing something normal but challenging with a model is generally enough for me. I do a quick (an hour or two) project, and see how it holds up. If I'm feeling like it's harder than it should be, I switch to a comparable model I know is good. e.g. I most recently tested Gemini Flash 3.5 for making a web app. It shit the bed...kinda worked, but was ugly and needed several bugfixes right off the bat. I tried the same app in Opus 4.8, which aced it with barely any extra conversation, it looked great (basic but clean, like it was intentional) without any effort.

I like reading benchmarks, but I take them all with a grain of salt. They're just to tell me if the model is worth even trying for my task. I've heavily used self-hosted Qwen 3.6 and Gemma 4 on a bunch of different tasks, and while the benchmarks consistently say Qwen is the better model, I simply don't find that to be the case for anything I do. I think Qwen is tuned for benchmarks, while Google couldn't give two shits about most of the benchmarks, they're just busy making unusually smart tiny models.