Question : How long do most people stay in Phnom Penh?
Answer : Of course you're not most people, but if you were, you'd stay roughly 15 days.
Question : Can you cut down on flight costs by changing the day of the week you travel to Phnom Penh?
Answer : The lowest-cost day to fly in March is Friday. Flexibility is paramount when booking travel plans in order to keep travel costs down.