I have read in professor Q's guide to Pathfinder wizards that
Unlike the Sorcerer or Bard or Oracle you never have to sit and wish that you had picked a different spell this level since in a minute to fifteen minutes you can easily have the spell you need ready.
Which is news to me, I thought until a Wizard had enjoyed a good nights snooze of eight hours they couldn't change around any of the spells they have memorised. Looking through the rest of the wizard class description I'm pretty sure I haven't missed anything.
Can a Wizard change a spell they have memorised for another without having to spend eight hours of rest?