It can be used in the context of explaining what changes that need to be made to someone's work for it to be acceptable. "You should have used established crypto library calls here instead of rolling your own SHA-256 implementation with probable bugs. Please fix it"
I also think it works well, better than "next time I would", for giving someone permission to do things. "You should have called me when the client asked for XYZ" sounds more forgiving and less venting than "Next time call me when the client asks you for XYZ". Or "you should have felt free to take a mental health day". It's more empowering.
Your first example is great -- in a correctible situation (as with code, or writing, or design), it works and is helpful. You should have used, should have written, should have drawn, etc.
But I respectfully disagree with your second example:
"You should have called me when the client asked for XYZ" is _exactly_ the kind of phrase I find unhelpful. All that does it lay blame - it says you did something wrong and in a perfect world you would have done something right. Your counterexample is the kind of feedback I'd MUCH rather hear.
"Ok, you didn't call me when the client asked for XYZ. That is fine. If it happens again, call me." It addresses the situation that happened, emphasizes that you are indeed forgiving, and gives guidance about how to handle it in the future.
I agree my second example was poor. The intention was "should have" would be used when you had an optional, not imperative, future choice. "If you thought something was wrong, you should have (implicit or explicit) felt free to call me and escalate it." And (upon reflection) I don't think it really expresses that at all.
I still feel like "If you needed a mental health day yesterday you should have taken one" can be empowering more than "If you need a mental health day in the future, take one", for the same reason that the middle example is poor. It shifts agency (and blame in the second example) to the person you are talking to. But I no longer even feel as confident in that example either, and would welcome pushback or not on the point.
Thanks for pointing it out. I'll try to be more aware of that going forward.
>"You should have used established crypto library calls here instead of rolling your own SHA-256 implementation with probable bugs. Please fix it"
in this case, i would say something like "hey, we need ot[or should] use a cryto library here since it's battle tested, rolling your own crypto might have issues [yadda yadda yadda]".
it makes it feel like it's not a single developer decision, but a team/company wide one.
I also think it works well, better than "next time I would", for giving someone permission to do things. "You should have called me when the client asked for XYZ" sounds more forgiving and less venting than "Next time call me when the client asks you for XYZ". Or "you should have felt free to take a mental health day". It's more empowering.