I learnt that it is better to wake DH and tell him I am creeping across him to reach my bag than to make him jump and think we have an intruder
I learnt that waterproof on the label of a jacket doesn't necessarily mean that.
I learnt that no matter how many pairs of socks the kids have you will need to treble it.
I learnt that no sleep is not conducive to happy marriage. (High winds, tent flapping, stress of being blown into lagoon = no sleep).