Here's our experience.
St. Maarten--ordered sandwiches in the morning. Room service asked why sandwiches that early, was I planning on taking food off the ship? My answer was honest, yes I was. Her answer, you aren't supposed to do that. My thought--hey, I have already paid for all my food on board, have hardly taken advantage of the offerings, so I stated I had read and heard of many people doing just this very thing and would like my food from room service. She complied and our food at lunch that day was just great.
Next day was St. Thomas and I felt a little bad about earlier experience so I ordered sandwiches the night before instead of in the morning. Sandwiches got "soggy" by the time we ate them the next day, though I had packed them in ziplocks. (partly due to condiments, lettuce, etc. making bread almost uneatable, partly due to length of time having been made). Will never do it this way again, will always order morning of and suffer the rudeness of the person on the phone at room service!
BTW When I asked for ice from room steward for cooler, both times he stated MANY people order from room service & pack lunch in this manner for trips ashore. HTH.