This does not happen, if you forgo one month of rent you have to have kept prices up significantly to make up for the loss. The only reason this could happen is if your loan terms are pegged to rent roll (usually only on commercial properties).

an example: $5000/mo apartment generates $60,000 a year; forgoing one month of rent means you have to now generate $60,000 of revenue in 11 months, which in a bad market will likely not rent for $5450 if it didn't rent for $5000. Your mortgage still continues to pile up along with insurance and taxes, so you can't escape the hole.