> rule of thumb is [...] trajectory [...] The goal should be smooth movement for all.
A more restrictive one is avoiding driver cognitive load and distraction. City driving can be exhausting. And attention budget allocated to one concern, is less available for that other thing that's about to unexpectedly bite.
> just because someone else is jaywalking does not mean you should follow them!
Another is attending to crossing as broadcast group communication. Manhattan pedestrians waiting at a light, will, quite reasonably, cue on the motion of others. Thus I might do a red-light crossing at a sprint-and-jog, solely to avoid misleading others with a "people are starting/walking across now" cue. Especially with tourists, and anyone with attention prioritized elsewhere.
Another is to threshold on benefit. Judgement errors will be made, so gate on the current case being worth that. There are people I can't comfortably walk with, because for low-payoff diagonizations, or avoiding a moment of red-light repose, they fountain social cognitive load with abandon. The pedestrian equivalent of car high-acceleration and speeding for negligible marginal progress.