I was wondering which time frame is more of the traditional one for releasing event type movies. I am including all the way back to the start of movies being made for the masses.

The two are similar yet quite different. The summer movies have one major movie just about every weekend, whereas the holiday season seems like a battle royale of a bunch of big ones all vying for attention at the same time.

Only difference IMO is that usually movies vying for awards come out during the holidays. It's much more rare to have a Best Picture come out during the summer. At least that's how I see it.

That's pretty much it. Some bigass mainstream shit that'll rake in cash and flicks that want awards in this period while the summer gets shit that studios want to make a lot of money.

As a very general rule, the holiday blockbusters tend to be a bit more prestigious (think LOTR, Titanic, Avatar, James Bond) and while the summer ones range from well-reviewed popcorn to complete trash. A winter blockbuster will have a better chance of getting a Best Picture nomination.

I didn't really clarify my question that well.

What I meant was, in the whole history of releasing motion pictures, which season has the longer standing tradition of event movies?

In the old days, I would go to the library to look up The New York Times film reviews in chronological bound volumes and check out the summer months and December and see which had the most event movies over the course of history. That's harder to do on the internet. My memory tells me the Christmas season, but I'd want to look over a few decades' worth of movie ads for those months to confirm it and I simply don't have the time.

I think Jaws kicked off the whole summer is for blockbuster mentality which Star Wars then cemented two years later. Prior to that, what were considered (potential) blockbusters were the studio's big prestige films and most of these seemed to open in December or fall/winter (AA consideration?). Godfather, Exorcist, many of the Bond films up until Spy Who Loved Me which started a summer cycle that ended with the last of the Dalton movies.