@Jens-Eskildsen Genuinely never done that. Neither has anyone I known. For a road bike. Obviously that's the done thing for crossers and what not. But if you are out on the bike all day you sre unlikely to go home to fill up.
We tend to literally just put in 10 litres and 300 mill.
You are right though 3% is so small it wasn't even worth mentioning it.