That's FRA for you.
My worst experience was arriving from ZRH and connecting to EDI. We arrived one and a half hour late in FRA and I had to run over to B to a Bus gate where I was told the gate closed 10 minutes ago.
Now the most insulting thing was that the plane to EDI was literally the one parked next to me when I arrived! I MEAN COME ON! But they didn't use the Z Gates but had a gate in B and drove the pax to the plane by bus... Great system. So instead of walking literally to the plane next to me (and making it) I had to run several kilometers (At least it feet that way) and missed the flight anyway. (Keep in mind that after I arrived at the B gate it still took 20 minutes until the plane to EDI pushed back as per FR24). The next flight to EDI was six hours later and at least I got 250.- Euro in compensation and a 30.- Euro meal voucher. But still, it's so frustrating.