I have often commented that DC released 30 comics a month, regular as clockwork, during the Silver Age. I based this on the fact that DC released about 3500 comics in the 1950s and about 3600 comics in the 1960s; simple math gave me the rest.
But it occurred to me last night that perhaps the distribution pattern was slightly different than I imagined. Wasn't it more likely that DC ramped up production a bit during the summer months, when kids had more free time? So I decided to do a little research into the matter. For reference, I used the Master List of DC comics compiled by Mike Voiles at Mike's Amazing World of DC Comics.
It turns out that 30 comics a month is a good rule of thumb. From 1955-1970, the fewest number of comics released by DC in a month was 25 in May 1961, while the greatest number was 39 in August 1958. But the vast majority of months the number of comics released ranged between 27 and 33.
Note that I am using "release date"; i.e., the date that the comic first appeared on newsstands, which was generally a month or two earlier than the cover date. There was definitely some seasonality to the releases, as can be seen by looking at the number of comics released by month over the entire 16-year period:
Note the oddball month of February in there; February consistently had more comics released than March, even though most years February had 28 days in it compared to 31 for March. If forced to speculate I'd note that back in those days, both Washington and Lincoln's Birthdays were holidays in most of the country, meaning kids had more time off school in February than in March. Why the jump in April? Spring break is my guess.
If we define the summer season as June-August, the seasonality becomes more obvious: