If your most qualified prospect submits a Letter Of Intent that includes a lower price and more generous terms than you had wanted or a less qualified buyer has submitted a more attractive LOI, then now is the time to negotiate with the stronger prospect. It's almost impossible to improve the deal once you have accepted (by signing) the Letter Of Intent. However, the buyer may find reasons to re_negotiate a lower price during the due diligence phase.
Athletics: When a high school senior decides on which college he or she would like to attend and receive an athletic scholarship to do so, a letter of intent is signed. Many sports even have a national signing day to keep the playing field level.