Since I play very casually in terms of time investment and im still able to get savages/ultimates done, I think that "casual" "midcore" "hardcore" is more something about difficulty rather than time investment

I think that -> Ultimate/Last 2nd-3rd tier savage floor/Criterion Savage = hardcore -> EX/Criterion/Chaotic Raid/Savage 1st-3rd turn + X4s = midcore -> everything else is casual