This would require about 10 courses per semester from the annual ones, and another 2-3 courses per semester from the once every two years courses, for a total of 12-13 courses per semester.
Examples? Looking at a few LACs in the Keck consortium:
Amherst: https://www.amherst.edu/academiclife/departments/geology/courses/1516F
About 3 introductory-level and 4 non-introductory-level courses per semester, with most non-introductory-level courses once every two years.
Williams: http://geosciences.williams.edu/courses/
About 4 introductory-level and 7 non-introductory-level courses per semester. It is not clear whether most of these are offered every year or every two years.
For a small non-LAC:
South Dakota School of Mines and Technology: http://www.sdsmt.edu/Academics/Departments/Geology-and-Geological-Engineering/Docs/4-semester-teaching-rotation-10-13-2015/
About 20 courses per semester, about two thirds of which are yearly courses, with the rest offered every two years.
For the student’s current school:
University of Maine: https://umaine.edu/earthclimate/undergraduate-studies/program_requirements/#sched
About 5 introductory-level and 5-7 non-introductory-level courses per semester, with a mix of yearly and every two years courses.
That seems to be more of a characteristic of well resourced schools, not whether they are LACs or otherwise.
That is not unique to LACs. Registration in upper level courses outside of one’s major would only be gated by prerequisites and course popularity.