I go to @sweetlacecharm’s school, and here at least it’s common for freshmen to take 12-14 units their first quarter. Usually it doesn’t impact much because most people end up taking 16 or 17 unit quarters often enough later on in college to make up for the credits. And unless the classes are in sequence or offered irregularly, taking one class fewer than normal in a given quarter isn’t a huge deal as long as you’re taking at least 15 units for most quarters. Though yes, if you make a habit of taking less than 15 units for most of your quarters you’ll either need to plan on a fifth year or take summer classes, barring AP or CC credit.