Reciprocal links remain a polarizing topic. For some subjects, it is perfectly normal, almost expected, that the link reciprocity percentage should be extremely high, approaching 100%. The more nichified your subject matter, the more likely it is you will have a high RP (Reciprocity Percentage) with sites that have the same or similar subject matter. [...]
The reciprocal linking percentage across the top five sites is over 80%, and for the top three, it’s 100%. And this reciprocity percentage is perfectly natural, believable, and in no way an attempt to fool any algorithm or improve rank..