Why are designs of whiskey bottls are different

Hello Community

Just wondering, why are designs of whiskey bottle different, example- rectangular, square, cylindrical, almost oval.

Is it done purposely due to following:

1. To make it look elegant?
2. Design team thought like that?
3. By design, u will not even know how much did u consume. U think quarter and actually it's half bottle?
4. To create a brand value by design?

Thinking as yesterday had Red label and I was fine after having a quarter of that (almost rectangular in shape)

Super happy after having Royal Stag as same quantity.

Sharing some of the pictures of Sunday Night party.

Cheers Everyone