More important than the number of comments is the quality. It's relationships that will build a brand here, not merely a lot of comments. It just takes a lot of comments to build the relationships sometimes.

A person is better to place 50 quality and valid comments a week than 400 rubbish ones like:

Yep
Yes
No
Ok
Nice post
Thank you
Cool
Wow...And so on.

That can come later, once the relationship in is established and solid.