There shouldn't be more than two dozen Christmas cards left to write.
(as plural only, always followed by of) A large, unspecified number of, comfortably estimated in small multiples of twelve, thus generally implied to be significantly more than ten or twelve, but less than perhaps one or two hundred; many.
There must have been dozens of examples just on the first page.
There were dozens and dozens of applicants before the job was posted.
An old English measure of ore containing 12 hundredweight.