Passengers who are do-it-yourself cruise bookers should know that some cruise lines' hold policies -- the amount of time between when you reserve a cabin and when you have to plunk down a deposit -- are shrinking. Carnival is cutting a day of its policy, from four down to three. And Holland America recently went from seven days to five. But others are staying put, for now, anyway. Royal Caribbean, which gives individual bookers a week to put down a deposit before the reservation is canceled, says it’s planning no policy changes. And Princess is staying true to its seven-day option as well.