The entire value of a 0% transfer comes from clearing the balance before the promotional rate expires. If a balance remains when the intro period ends, it reverts to a regular APR — often above 20% — and the savings evaporate. Divide the transferred balance (including the fee) by the number of promo months to find the payment that clears it in time, and commit to at least that.
Two behaviors sink most transfers. First, treating the freed-up limit on the old card as new spending room, which simply recreates the debt. Second, missing a payment, which can void the promotional rate entirely under many card agreements. Autopay for at least the minimum, and a hard rule against new charges, are what turn a transfer from a gimmick into a genuine payoff accelerator.