A term often heard during qualification where a OK, so we all know what the driver is, right. I've always liked the description that F1 drivers are like... must have a time on the board in order to progress into the next session or to finish as high up the timing sheet as possible during Q3.
Typically both the car and the driver are more ‘in tune’ at the end of the session and therefore the best lap time can come from the final run.
If there is a threat of weather or some other perceived risk that may see the session interrupted, the team may elect to put the car out early to do a fast lap to record a quick time. This is referred to as a ‘banker lap’.
Simply put – it is better to proceed with a lower time and stay in the running than to miss out by not recording a time at all.