FWIW in meditation you typically "visualize" air coming in through the nose, down the front into lower belly on inhale, then down and around the pelvic floor, up the spine, and around the inside of the skull back to the nose. That makes exhalation longer than inhalation: not twice as as long, but it could be something like 50%.
PS it is also the case in swimming: your inhale is typically shorter than exhale.
PS it is also the case in swimming: your inhale is typically shorter than exhale.
