But hardly ever ... admiral.
This one is very variable, i.e. the study time vs. outcomes.
Majors, personal preparation, IQ, other responsibilities ... all these and other variables may play into this.
There is LOTS of programmed study time that for some becomes "ho-humming" time and for others becomes pressure of not enough time. Some students become frustrated that there is not enough time or focus on a specific course or their major subjects. I know some who've left because they were not getting enough of XYC subject matter, or they were frustrated that due to the multi-tasking expectations and requirements ... but that's off subject.
Mids'll give you an up-close, personal reports, I'm sure.