You're supposed to be able to book your entire trip worth of dining 180 days out, as long as your trip is 10 days or less.
Instead of calling back everyday, you call 180 days out from the first day of your trip and make that day and every day of your trip in one call (up to 10 days worth).
That said, some CMs have allowed people to book 190 days out but that was not the original intention. The intention was to allow on site people to avoid calling back everyday for a week to get their dining reservations made.