The synodic month of the moon (29d, 5) is shorter than the length of the calendar months in 30d and 31d, during each of which one or two full moons will necessarily occur.
A month without a full moon can only be February. This is a rare case. The last time a month without a full moon was February 1868, and the closest was February 1999.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.