They simply do not exist. The general rule of 3 hrs of study a week for each hour of course credit is no joke. Such experiences have led to the classification of a person carrying 12 semester hours as a full-time student. This may be vastly different from your experience in high school. Knowing the material.
Understanding is what has to come first, but knowing is beyond even that.
Knowing requires a degree of familiarity and usefulness of the material that cannot occur overnight. Cramming doesn't work.