There's a lot of ways to do it, and I think it just depends on the type of product you have and your overall strategy.

Some brands have different accounts divided by region: one account for USA, one for Europe, one for Asia.

Some might do it per country or language. One for Germany, one for France, one for UK. Or one for English, one for Spanish, etc.

Some might do it per product.

Some might divide accounts based on the type of content: one account for news, one for pics, one for links.

Some might do it all under one umbrella.

Some might have one main account, but have some smaller additional accounts for different purposes.

There's too many factors that go into it to give just one answer.

If the different products will live under different brand identities, then it makes sense to use separate accounts.