My wife and I fly DFW-FRA-TIA a couple times a year on LH, and we've noticed that sometimes the DFW-FRA flight will land at a B gate,
and when we disembark, there is usually a LH employee waiting at the end of the sky bridge to let passengers connecting to
a non-schengen B gate pass-through, bypassing security and passport control. This seems to be hit or miss, as sometimes we arrive at a bus gate
and we have to take the Skyline train to B and pass-through security again. But if you are flying LH from the US and land at a B gate, and
you are connecting on another flight to a non-schengen destination, be sure to look for a LH employee letting you cut through to
the non-schengen B gates.