Actually some “merit” students hit a wall in college because they didn’t have to study in HS and don’t have study skills. Even at top schools out of class time will vary by course, but bottom line is that a lot of it is on you. D was great math student in college, but she did all problem sets even if not graded and then redid them before tests. Unless really crunched for time she did readings that were recommended but not required. She went to class. Both my Ds began papers far enough ahead of time to take advantage of prof offers to look at outlines or rough drafts.
As to exact question, I’ve seen the 2-3 hour outside for one inside class as well and that seem to be true for older D at LAC that was ranked top 15 for how hard students work (if you believe in rankings).