I respectfully disagree,
@A1Janitor. Many applicants at this stage don’t know 100% what they want. Having multiple meaningful options — and new information — can dramatically change their decision calculus.
For example: DD declared in the 8th grade that USNA was her first choice. She also applied to USMA and USAFA, because she was willing to serve as a commissioned officer in any of those branches, i.e. her Plan B. With both USNA and USMA offers in hand, she attended a WP Founders Day dinner and was lobbied hard — respectfully, but hard — by the alumni there. She came thiiiiiiis close to flipping to USMA. In fact, I thought for sure she would.
For other candidates, it could be something else that prompts a change in preference, e.g campus visit, conversation with a grad, deeper dive into possible MOS, and so forth. So I say, keep all options open for as long as you need to make a smart decision. I’m one of those who does not subscribe to the “you’re hurting others” line. You’ve earned your nomination and offer of appointment, and you deserve the right to make your decision in the time allotted.