As far as latitude to make changes ... the last round of design and redo happened after a spirited (to say the least!) public discussion and I think everyone was happy about that process.
More minor changes have frequently resulted from e-mail or forum requests, as people have time to tweak it here or there. These haven't always been publicized ahead of time. Some things are just too obviously useful to worry about process.
I think common sense is the key. Just ask yourself ... "if Don were to do this, would I want to know about it in advance and be able to comment before he did it?" (or "if Jeff" or "if Dave" or whatever floats your boat) and if the answer is "yes", then it is safe to assume it's best to ask the community before plunging forward.
That's what I think at least.
