After having added web-of-trust to gossip, I think that 2-degrees of separation is good enough for now.  All the people I follow, plus all the people that they follow.  I follow 262 people.  They follow 17751 people.  That is 67x as many people.

Some people are suggesting 3-degrees of separation.  I didn't try it, but I suspect this would not grow another 67-fold because the nostr community isn't big enough for that.  So if you do 3-degrees of separation today, you'll get just about everybody on nostr that isn't a spammer... which is ideally what we want.  So go for it if you dare.

However, there is a cost to maintaining 3-degrees of separation data.  As nostr grows, your table will grow to probably over a million people. And you will need to keep the contact list data for all of the people at 2-degrees of separation, so that as they follow and unfollow people you can apply increments and decrements to those people's WoT score.  For me that is 17751 lists of public keys... which I feel is too much data for a client to be maintaining just to slightly reduce spam false positives.

Feel free to disagree if you feel the juice is worth the squeeze.