Looks like crontab revision 1.11 commented out the /etc/monthly job.

But its log entry doesn't say that and doesn't say why. This was back in 
1997.

The man page says:

  The /etc/monthly script is run, by default, in the morning of the 1st of 
  every month, on a NetBSD system.

  There are currently no monthly tasks.

Should the man page say it is commented out?

  Jeremy C. Reed