"When passenger volume exceeds border control capacity" my A$$!! In Frankfurt, the clustered situation resulted in a line to have passports visually inspected in excess of 100 meters long, and then there had already been a requirement for facial recognition.
BUT THE REAL bottleneck is federal officers in the kiosks--one third were empty!!! Grrrr. Inexcusable, so much for German precision.
And that is after delays getting around the airport due to signage problems and personnel ignorance/unhelpfulness.
My solution? I am contacting the vendors in the airport and telling them about the tens of thousands of euros they are losing because passengers have NO TIME TO SHOP! Let THEM bring the pressure. I know I had a lot of euros to burn.
Better schedule longer layovers. Three hrs just wasn't enough!