Biking in Heels posits that differences in the way our traffic signals work for pedestrians explain why Bostonians dart every which way from every direction, while Cantabrigians are more thoughtful, even when jaywalking:
In Cambridge, the city has had a policy for a long time of concurrent walk signals, so pedestrians have a right of way every time the cars going parallel have a light, so there's never much of a wait. There are regularly spaced crosswalks in areas without closely spaced lights, and where those crosswalks are on high speed roads, there are lights with "on demand" buttons. The signalized crossings controlled by the city of Cambridge (for example the ones around Fresh Pond) operate almost immediately after pushing, with only 30 seconds or so of delay to safely slow and stop traffic. In most places, especially pedestrian dense areas, there are countdown timers too, so that the pedestrian knows exactly how long they have until the light will actually turn.