When I did a b2b at OTP a couple of weeks ago, arriving at gate 7, the belt barrier into the transfer channel was in an L shape, the entry pointing towards the rightmost security checkpoint.
I was queuing for that checkpoint, but then another member of the border force appeared, whom I asked about going straight through; a quick glance at our passports and we were through.
I got the impression that either he or his colleague in the booth would have had to check our passports, and we couldn’t have just dog-legged around the belt stanchion and into the channel without breaking their rules