One thing is clear for search engines: If a website receives links without an own effort, it must have a certain relevancy and quality, otherwise nobody would link to them. Links which develop by quality are named as natural link structure.
As soon as you want to run a targeted offpage search engine optimization, you automatically leave the natural linkbuilding. Now you work for getting links from other websites. The problem is: Google rates a simulated linkbuilding significantly worser than a natural link structure.
You have to consider for your search engine optimization, that there are no abnormalities. If you for example perform a link building day and generate 100 new links this day, Google will become clairaudient. It is not naturally, that a normal website receives a lof of new incoming links at once. If the search engine notices that, penalties become possible.
In a natural link structure it normally does not happen, that there are significantly more links from websites with a high page rank compared to the links from websites with a lower page rank. For google it seems additionally unreal, if there are only follow links in a link structure - a healthy link structure contains a certain number of nofollow links.
A natural link structure does normally not allow, that the bigger part of the links originates from a special source. You may for example collect links, if you comment a lot in posts of blogs or in forums. But in the long run it stands out if there are only such links and no links from blog articles or directly from other websites. Of course you may use links from comments for the linkbuilding. But you better do not restrict yourself to a single link source.
Linkmads may support you with a natural linkbuilding. The via the text link marketplace booked links are indeed with costs, but you get in return several advantages at once. First of all you receive topic relevant links with a minimum of effort. The Linkmads team takes over the quality control for you, because the offerers have to fulfill special requirements before they are taken up into the offer catalogue. Additionally you do not have to spend much time for the administration, because Linkmads takes over the complete processing of the link booking.