Confused about "default"

I’m bit confused what exactly should I do

I have x posts, for example

http://www.domain.com/best-uk/ (call it 1)
http://www.domain.com/best-au/ (call it 2)
http://www.domain.com/best-us/ (call it 3)
http://www.domain.com/best-ge/ (call it 4)
http://www.domain.com/best-be/ (call it 5)

these have majority of identical content

As far as I know I should link eatch other with hreflang

ie:

1: hreflang to 2/3/4/5
2: hreflang to 1/3/4/5
3: hreflang to 1/2/4/5

and so on…. This is correct, right?

But when using your plugin it always automatically adds the x-default to every post… So all US/AU/UK/GE/BE are flagged to their language/country and default at the same time – isn’t that wrong? Shouldn’t there be just one detaut (primary) post?

Thank you

https://ww.wp.xz.cn/plugins/hreflang-tags-by-dcgws/