Firewood - fit more chopped small or large?

Hope this is the right forum to ask , apologies if not.

I recently ordered a some bags of firewood (came in those white builders tonne bags). The timber was cut noticeably shorter than the previous load i got from another provider. Given that presumably there is more work in cutting more smaller pieces that larger ones I couldn't help but wonder if the supplier is padding the bags by doing it this way?

So thats my question, if for example you have a bag of timber cut into about 20cm lengths, is there more timber in the same bag if its cut into 15cm average length. My wife reckons the smaller timber will have smaller spaces so its will have more but I'm not sure I agree.

What do the woodcutters here think ? Thanks!