I hate that it's true, but things like this make outputs night-and-day for me. This is the difference e.g. of a model writing appropriate test harnesses, or pushing back on requirements, vs writing the most absolute horrible code and test/dependency injection I've ever seen in pursuit of the listed goals.

Similar to adjacent commentors I've tried to be better at enumerating what I consider to be best practice, but I couldn't argue in good faith that instructions like these produce no noticible improvment.

(As with all things AI, it could all be percepion on my end, so YMMV, wish there was a better way to concretely evaluate effects on outcomes of different rule sets / instructions / ...)