Active work should mostly be hillclimbing, or at least more exploratory. The search space is very large and you typically find a lot more low-hanging friction than you'd think by just running a broad battery of sessions. And I'd pair active hillclimbing work with feature launches/product work - essentially part of releasing new things is QA-ing them against coding agent workflows.

The test suite eval style is useful and mostly a complement. You do want regression tests on critical features.