Tad container size?

I Know this thread has been done before and I've read through several different ones as well. I was just curious what size container is just too small and what is just plain overkill for individual thumbnail tads (particularly vanzos)? The smallest I've seen is 5oz solo cups, and I know broms only hold several oz of water.

I'm really curious to what too small of a container is though? Are 3 oz, 4 oz, 8 oz containers okay (preferably glass)? Are any of these just way too small and one should stick to a certain size? Or would they work if they're given frequent water changes?

I know the norm is anywhere from 6-16 oz whether deli cups or mason jars. I've also read both views of the spectrum as well of bigger cups being better and then the complete opposite for smaller containers allowing tads to find food easier.

I was just curious on others experiences and thoughts.

Thanks