There is a little group of us PSN players to regularly duel. Usually it starts as 2 or 3 people but as more people get on it ends up as a little FC. Anyways, only a couple buff, period. Unless their build is meant to buff, we really don't buff. I am not counting grass. Most of us grass besides a few. If we're in the middle of a match and we both grassed at the start of the match, we both will grass in the middle of the match also if we have been going long enough to run out of the buff.
But, if at the start of a match only one of us grasses, usually you can only re-grass if you can get away with it. For example, Rant doesn't grass. If i'm dueling him and i grass at the start of the match, i won't re-grass in the middle of it. If i do, i don't expect him to just let me, which is why i just don't do it (i probably have before but it's not an everytime thing.)
It really depends on who you're playing. Obviously everyone has the respect to let you do whatever you wanna do at the start of the match, but i don't expect everyone to have the same in the middle of the match. I kind of see that as for example, re-CMW buffing in the middle of the match (obviously not the same, but you understand.)
Grass eaters lets other grass eaters eat grass in the middle of the match. I don't expect non-grass eaters to let the grass eaters, eat their grass in the middle of the match. Ya dig? That's how we do it in our little circle of duelers at least. (referring to re-grassing.)