Cub Scouts meet in their dens once each week, and a pack meeting is held for all Cub Scouts and their families once a month.
Beyond that, it depends on the den and pack: A den may hold a special activity, such as a service project or visit to a local museum, in place of one of the weekly meetings or in addition to the weekly meetings.
Likewise, a pack may conduct a special event such as a blue and gold banquet as an additional event, rather than a substitute for its monthly pack meeting.