I've seen people quoting "google maps told me to do this" and it involved journeys in London including buses and Underground on journeys in some fantasy world where everything runs precisely on time.
The TfL Journey Planner allows only 4 minutes for passengers arriving on GWR at Paddington to connect with District/Circle Line services, comprised of a 2 minute allowance for the scheduled arrival time plus a 2 minute walk, which is a pretty heroic assumption. It also suppresses onward connections via Paddington's H&C platforms unless absolutely forced to do so, which causes it to display nonsense itineraries e.g. for Reading to Royal Oak it recommends Reading - Paddington - Paddington District/Circle platforms - Edgware Road - Royal Oak. D'oh!