The Neue Galerie, a museum in New York specializing in modern German and Austrian fine arts, is currently showing an exhibition on the 20th century German artist Otto Dix. Dix is associated with the Secessionist as well as the Neue Sachlichkeit (or New Objectivity) movement.
When one thinks of art one thinks of artistic license, the freedom to embellish, simplify or remove what is seen or perceived. But in the case of Dix his portraits of individuals capture closely the clothing they actually wore.
For example, below the 1923 painting entitled "To Beauty" features a self-portrait of Otto Dix himself. Notice the close positioning of the jacket buttons on this two button peak lapel suit with slanted pockets. The closeness of the buttons on the jacket front is a bit unusual. But if you go to the exhibition, you will see a black and white photo of Otto Dix at the exhibition entryway wearing a similar jacket with compressed button spacing but in notch lapels and flapped pockets.
Below is another example of a sitter (c. 1922) wearing a jacket with closely spaced buttons. Perhaps it was a sartorial regionalism in Germany at the time or a carryover from formal frock coats.