I think the advice is good, though pretty obvious.
My son was deferred from one of his high choices. He sent a couple update letters highlighting actual new info and continued interest and he was ultimately accepted (but did not attend.) My daughter was waitlisted from her #1 choice. She kept in contact and even scheduled a 2nd campus visit. On our way to that visit came the happy news that she had moved to ‘accepted.’ She is attending there now.