Assuming you mean throwing on random episodes, less lately due to focusing on new turtles media, that's for sure. For many years it was a few times a month, last couple of years it's been just a few times a year. I've seen it so much, there's a bit of fatigue, it's still too fresh in my mind. But I will always love & re-visit it, despite its flaws & how much of it I have committed to memory.
If you mean doing the series from front to back... never?
I just jump around as I please, but have of course seen every episode multiple times.