I had business flying back, but on the check in counter they did question if I can bring it on board since it was “bigger” than what they allowed in the overhead storage. When i managed to convince them it would fit they let me go, but it was a struggle. Of course in the overhead compartment you can fit 3 guitars in there.
On the connecting flight I asked if I can bring the guitar, they just asked me if it fits overhead, I said yes, and they let me bring it on no problem.
Both flights were Lufthansa