I am still pretty new to Marriott - moved over after hitting LTD on Hilton, and qualified for Ambassador on my first full year (2024, will do so again this year based upon current travel plans).

My strategy

• For vacations Book the base cash / point rate at the property I want.
• Request only the NUA options that will get me what I want.
• Have a backup (Hilton mostly) property.
  • It makes me feel better (more spiteful?) to move my business and spend for that stay
• Cancel the moment i get a reject at the 5 day window. Move my business (for that trip) to Hilton.

I do suspect the more seasoned elites (Flyertalkers specifically) are going to do much like what I am doing.

Edited to add: I don't blame them for trying to monetize every room they have, and I also understand the business behind breakage for them is part of the strategy. I likewise understand I am sure they don't care if I move a stay or 3 through the year. I also don't get overly worked up about it.