it depends, whether or not you like to hear it. And "competitive niche" can mean anything, so it depends on that, as well because there are many competitive niches but the competition is not equal across all niches and keywords.
And like
@Turbo B. said, it's mostly about RDs, not backlinks...
How many website do you need if you wanna build your own pbn ? (Is 30 enough ?)
it depends! Is your competition tough? Are you in the banking, loans, insurance, medical, SEO, web hosting, travel niches? Then no, 30 PBNs are not enough, you need 100s of them. Are you in the pets or arts & crafts niches? Then 30 might be enough, but it's still not straightforward because it depends on which keywords you are targeting and which brands / companies rank for the same keywords.
Do you absolutely need expired domain on your pbn or 4 month of consistant posting is enough ?
you don't need expired domains to build a PBN but expired domains help because 1) they pass the sandbox that new sites usually get, and when you consider the fact that sandboxes can last anywhere from 3 months to 2 years or more... well, you can see why expired domains are important... and 2) they usually index and rank better
4 months of consistent posting in google's terms = 1 day of consistent posting or 1 million years of consistent posting. In other words, it doesn't matter how long you're posting content for "consistently" if you're not consistent. Which means, you either don't bother being consistent at all, or are consistent indefinitely. That's why it's usually recommended to be consistent at your own pace, but be consistent nonetheless instead of being consistent for 1 month and then let your site rot for 3 years. Sure, sometimes sites do get and keep top rankings without much interaction, but these cases are rare and random. If you want to get and stay up top you need to slave your life away or outsource everything, or not bother with SEO at all if you crave freedom and laziness like me. These are the only options, unfortunately....
