Answer by Thunder Rabbit for Cron job to run on the last day of the month

Adapting paxdiablo's solution, I run on the 28th and 29th of February. The data from the 29th overwrites the 28th.

# min  hr  date     month          dow
  55   23  31     1,3,5,7,8,10,12   * /path/monthly_copy_data.sh
  55   23  30     4,6,9,11          * /path/monthly_copy_data.sh
  55   23  28,29  2                 * /path/monthly_copy_data.sh