If you're just working on your "manuscript" for later final typesetting, you can of course use all abreviations that you and the typesetter agree upon.
But if you're preparing a score for performance or publishing you should notate each instrument individually. Performers need to follow the score for their part, even if using (for lack of an individual part score for their instrument) a complete score with all the parts. They cannot have their eyes wandering across the page looking for possible indications that may be relevant to them.
Perhaps there could be a case for "global commmands" for orchestra conductor scores, but it would probably create more readability problems than it would solve and it is not the convention any way, as exemplified below.
