This was common for animated Saturday morning shows in the '70s. A number of other Filmation shows only had one season that kept getting rerun for years. I grew up seeing the same episodes over and over and finding it normal.
Me too. And it never got old. I watched the same cartoons over and over, but if I got distracted by something else, well, there you go. Kids are kids.
I was 13-14 when TAS aired. I'd try to watch when I could, even if it were a rerun. In those days there was only one TV in the house, and the younger sibs often beat me to it and watched whatever it was they liked.
If I didn't like what was on, I had to find something else to do. Read, go outside, ride my bike, whatever. There was no internet, no gaming consoles, nothing. We literally had to think outside the box.
But in the 22 episodes of animated Trek, I still wonder why there was no episode number 12?