How many is usefull create backlinks with domain or brand anchor text?

hello.

i have many backlinks with many phrases.recently i buy a backlinks from PR 5 and PA +50 with my brand anchor text.(just brand without any other word).then my website ranked well in all related phrases.
how many is usefull create or buy with domain/brand anchor text?if i continue buliding backlinks with brand/domain anchor text, can i ranked more in all related phrases?

also, brand and domain is different?brand is better or domain name? none-english websites domains are different with their brands.

The more authority links = the better ranking. But buying / making links with the same keyword in anchor can trigger penalty from google, so make sure you differencify your links and sources of it.