A typical journey is one where there are delays going through security - on average it probably takes 10 minutes, but that includes the 1 minute occasions as well as the 30 minute trials. It also seems fairly typical (about 50% of the time) that BA1313 is given a remote stand instead of a jetty so we have to get a bus to the terminal.
Therefore my typical journey through T5 is medium length and frustration, and a fluke is when it goes like clockwork or takes forever. Anything outside a few standard deviations is worthy of note, whether good or bad.