This is a phenomenon I've noticed others report as well. It appears that many 90s cartoon series were only produced for one, maybe two years. They were then aired as constant reruns for the following 2-4 years. We were just too young to take note or care, at the time.
I recognized this as a kid and it pissed me off so much. Watching the same episodes of tiny toons over and over was maddening. They were only 3 seasons. At least Animaniacs were around for 5 seasons. They had a good run.