Tyson will end up walking the same route, over and over.
In part, this is familiarity, taking the direct path to the nearest supermarket to buy extra milk is the simplest course of action. However, when Tyson is on edge, it reaches a point where his behaviour couldn’t be called anything other than patrolling.
He’ll take Lily and Bobby with him, and fastidiously adhere to one route around an imaginary perimeter around his apartment: one that stretches far enough to include The Biscuit Tin and the nearest Underground entrance. Tyson will walk that path over and over again, until he’s too exhausted to continue or other responsibilities call him away.
There is never a point in that patrolling where Tyson goes ‘oh, okay then. There is nothing to be worried about nearby’. He falls into a trap of tunnel vision and paranoia that would have him marching for hours on end.