I don’t often use them, but was looking up traybake recipes earlier - virtually all stating 8 to serve 4 people.
Those I usually buy are pretty big and TBH I’ve usually used one each, obviously with plenty of potatoes/rice/other veg. I’m sure it’d be different if you had hulking great, permanently ravenous teen boys to feed, but is it odd to have just one each?
It’s not a question of economising, BTW, I just feel that one per grown adult is enough.