Are there rules for the different ways to say 4 and 7 in Japanese?

Question:

I know about not using one of the versions when talking about months, but are there any other rules? More specifically, when people are counting off? I was in a group of people, and we wanted to do something different for our count off, so we decided to count in Japanese. We used "yon" and "nana" instead of "shi" and "shichi" and when we counted off, a few girls from another group yelled that we had the numbers wrong, and began to count using "shi" and "shichi". One of them supposedly lived in Japan for years, so it made me question myself. Are there rules about 4 and 7 that I don't know about?

Answer:

There is nothing wrong with using yon and nana when you are just counting numbers.

Those girls just wanted to interrupt.