Short answer: yes.

Much Longer Answer:

Yes, 65 episodes was the standard order for a daily animated series. This dates back to the early 80s--the first two animated series created for first-run daily syndication were He-Man and the Masters of the Universe and Inspector Gadget, both of which premiered in the fall of 1983 with 65-episode seasons. At five episodes a week, that's 13 weeks of episodes, meaning the entire cycle can be shown four times over the course of a year.

Batman: The Animated Series didn't premiere until 1992, which puts it a decade into this trend, and long after all of the great cartoons of the 80s--your Transformers, your G.I. Joe, your My Little Pony, your other shows not produced by Sunbow and based on Hasbro toylines. What was notable about BTAS, however, was that it was the flagship series for Fox Kids and the one that announced it as a major force.

SIDEBAR: The Fox Network was--after many years of trying--the first successful attempt at creating a "fourth network" to rival NBC, ABC, and CBS. It was effectively a full syndicated network, and while the Fox shows were on in the evening blocks, the rest of the day was your standard syndicated talk shows, game shows, miscellaneous cartoons, old movies, et cetera. (I grew up in the suburbs of New York City; here NBC is Channel 4, ABC is Channel 7, and CBS is Channel 2. Channel 5 (WNYW) became "Fox5" in 1986. There were two other syndication channels, Channel 9 (WWOR) and Channel 11 (WPIX), which later became UPN and The WB respectively when those were launched in January of 1995. When those two syndicated networks merged into The CW, WPIX retained the programming. WWOR had--oddly enough--been purchased by NewsCorp in 2000 and run a combination of both UPN and Fox shows, despite Fox5 already existing. It later became home to another syndicated network, MyNetwork TV, which was kind of a disaster but technically still exists. Go fig.)

SIDEBAR OVER.

Fox Kids started its run in 1990, with a three-hour block (intended for Saturday mornings), comprising Fox's Peter Pan and the Pirates, Attack of the Killer Tomatoes, Bobby's World, Tom and Jerry Kids, the third season of the previously-standard-syndication game show Fun House, and two shows I personally have zero memory of, called Zazoo U and The Piggsburg Pigs. Because at this point Fox Kids was weekly only, each of these shows had an order of 13 episodes--again, allowing the full run to be shown four times. The exception to that was Peter Pan, which--for reasons I cannot surmise--seems to have aired a new episode every week from September 10th 1990 through December 2nd 1991...for a total of (say it with me) 65 episodes.

(There was a second season, but it's not really relevant here.)

Batman: The Animated Series was Fox's first show created specifically for a five-days-a-week run, and as such had a 65-episode first season. (For a while, it actually ran six days a week, with an episode also included in the Saturday morning block.) What's important to note vis-a-vis your question is that it was syndicated from the jump, but as part of a block--it was not aiming for syndication, per se, because it was already there.

ADDITIONAL BIT OF INFO: It is not uncommon to find shows that ran weekly for their first season and daily for their second--those series would have a 13-episode first season and a 52-episode second season, for a total of 65 episodes. The two that come immediately to mind are Gargoyles (which ran every Friday as part of the Disney Afternoon in its first season and daily in its second*) and Exosquad (which was in first-run syndication both seasons).

*yes, there was technically a third season of Gargoyles, which was 13 episodes run weekly on ABC (not in syndication), but we don't talk about The Goliath Chronicles. We don't talk about it. EVER.