You should not be concerned. This is extremely common--especially these days. While some sold-out situations have occurred over the past year or two, they remain rare, and TBH, EHI (the parent company of Enterprise, National, and Alamo) does a much better than average job managing their inventory, so we don't expect that you'll have any issue.

As an aside, there is absolutely no reason to waste your time monitoring your reservations for lower rates. AutoSlash offers a service that does this for free. You just plug in some basic details and then we constantly re-price your reservation and let you know if a better deal comes along. It's literally the easiest way to save money. Be lazy. You have our permission.

Safe travels!