This is really good advice. I found myself on gab.ai mostly posting newslinks, in the hope of beig "First with the Burst". :) When I started posting Steemit links, I told myself to not post two in a row: to post at least one "regular" link before posting another one to Steemit.
Strangely but interestingly, one of the psychological reasons behind bullhorning is a workaholic ethic. The guilty feeling which tells you that any social postings is "goofing off." I had to work this through my head!
Yes, we need to mix it up. Posting from one source all the time or just one type of content gets old as well. People love to see different types of content.
When I first joined Twitter I did not understand how it worked and just shared content like crazy without engaging. After a few years I learned my lesson.
Funny thing about life - we gotta learn a lot of skills the hard way. ;)