Filou and Tigris have their teeth cleaned. Tigris one time up to now (he's seven), Filou (also 7) 3 times -he builds a lot of tartar. The last time with Filou was 3 weeks ago. I cam smell it from his breath and see it from hís gums (red) when it's time again.
My vet says it is as with humans: some build more tartar than others. My dentist confirms that.

Of course food can help -but just a little.

Filou and Tigris are independent cats who say :If you brush my teeth I'll rip your arm off.

It is a little stress for the cats. They are anesthesized and cannot eat the night before. But they are happier after. The first time I did not know about it and Filou must have had pain. He was much friendlier after the cleaning.

It's definitely not a money making issue. Go for it