What goes through one's mind? Hmmm.
a lot of discussion-stuff all in one place at one time. a lot of discussion-activity going on everywhere.
many discussion-events. many instances of discussion-events. many instances of individual discussion-events.
a lot of discrepancy? This doesn't sound exactly right to my ear, but I suppose it would be
a lot of discrepancy-stuff. OR a big discrepancy.
many discrepancy-things. many instances of discrepancies. many times finding a discrepancy.
Since these are things "going through one's mind" they are not necessarily grammatical as stated above!
CJ