A precision cut sleeve that shows some white is a trademark of a custom tailored suit! It’s a shame that many people (including high ranking politicians) these days wear jacket sleeves that are not tailored.
Here is a picture of French Defense Minister Jean-Yves Le Drian, accompanied by Itsunori Onodera, reviewing an honor guard detail in Japan. (Photograph courtesy of Reuters)
Outlined in green is the correct way to have your sleeves tailored, while red indicates fail.