Best anchor text ratio for tier 1 currently ?

I have been gone from SEO/IM for a while been trying to catch up on everything and one of my big questions right now is anchor text ratios for tier 1. People have been saying getting tier 1 ratios right is a must in current SEO state but I have seen a few different recommendations. One guy even said you should only have 1% of tier 1s with exact match anchor text, is this true? Also I have seen people saying that you should only use your exact match keyword anchors on the highest of powered of your tier 1s which is why a lot of people use PBN links for this as part of their tier 1 is that true ?

So lets say I create 50 web2.0 tier 1s should I just have maybe 1 (or none at all) of those with the keyword I'm going for ? and the rest be naked urls/LSI/generic/ect. And then I have lets say 10 PBN anchors with my exact match keyword?

Thanks

The best anchor text ratio is the anchor text ratio that your strongest competitor has.

10% main keyword variations
60% naked URL variations
30% everything else

majority of websites with natural backlink profiles have most of their anchor texts as naked URLs

20% Main Keywords, 50% naked URL's and Rest 30% with Generic ones.

Seems to be some variation to what people think, but the constant would be to have a large portion of naked urls.