I was just speaking with a caregiver who told me that she was quite sure that the pet cats that run down from the flats above are not being fed, because they also eat with her community cats. While cats don't tend to overstuff themselves (though some do!), just because they eat when you feed them doesn't mean that they are not being fed adequately by someone else.
I know in one area that we went to, that they set up a security camera to find out whom was feeding the cats. They found in the course of one day that four or five people (who all came at different times) were feeding the cats. All of them were of course in the dark about the other feeders. The cats were eating happily every time.
It would be good if you can to try and find out if anyone else feeds your community cat too. That way you don't need to replicate the work. It may be difficult to find these other caregivers but if you do, you can split the work.