Gadol > any time spent beyond that necessary to engage in essential life-supporting functions
I think, this is a definition of Toraso Umanoso.
I also think some people here define “learning” time narrowly. IMHO, any discussion that involves clarification or application of Torah principles qualifies. Of course, if the discussion is done badly, without integrity, trying to defend your position rather than clarify the truth, it is bad Torah learning. In that sense, CR is riskier than memorizing a Mishna.