Brace ratio standards?

[Jacobezzell]

Thanks for everyone's help so far on my playhouse plans. After some sketchup hiccups I'm rolling right along.

Question is, besides generally that a longer brace is better than a shorter brace, is there a rule of thumb for how short you can get? Talking about between a post and plate. Should I try to be at 1/3 from the joint, like planning a truss? Or is less ok? I tried searching for other threads about brace span or brace size but didn't find what I was looking for.