If you took the phone out of airplane mode on arrival (assuming there WAS service) every time you got a text/email you would be charged $10/day for that day.

Makes more sense to only take it out of airplane mode on a day you need it. All your texts will then arrive and you can makes your calls.

Then return it to airplane mode until needed again.

It's $10/day only on the days it is used not a blanket $10/day