Each piece of that advice is reasonable on its own. Stacked together, the rules price most buyers in higher-cost markets out entirely. Twenty percent down on an expensive home is an enormous sum, and a 15-year payment on top of it is out of reach for plenty of people who could comfortably carry a 30-year payment. Dave's rules assume most people are bad with money, and there is truth in that framing: the less financially disciplined you are, the more those guardrails protect you. The more disciplined you are, the less you need them. Jeb's preferred alternative is a 30-year fixed paid voluntarily on a 15-year schedule using an amortization table. You get the payoff speed when you can afford it, plus a fallback to the lower required payment in a tight month. A strict 15-year loan gives up that flexibility. One more cost of the rule: waiting years to reach 20% down means waiting through whatever home prices do in the meantime, and nobody can promise which direction that goes. If the guardrails fit how you handle money, use them. Just know they are a preference, and a restrictive one, so the choice belongs to you.