by Derek Haines on Just Publishing Advice site:
When a potential book buyer clicks on your book link, where do they end up?
If they live in Scotland, do you send them to Amazon US? If they live in South Africa, do you send them to Amazon UK?
If you do, you have probably lost a great chance to sell a book because book buyers in the UK cannot buy books from Amazon US, and nor can South African buyers use Amazon UK.
Do you open publish? Yes? Great. But how do book buyers who use Apple iBooks or Kobo buy your book? Certainly not from your Amazon Kindle link.
Using one store link for your book promotion, such as to Amazon Kindle US, will work for US buyers, but what about the rest of the world?