Part-Time College

In the US, most colleges follow either a semester or quarter system. A semester system is two class sessions during the typical nine-month school year and the quarter system is three class sessions during that nine months.

A standard full class in the semester system is three credit hours because you typically spend three hours a week in class for about sixteen weeks. The equivalent class in the quarter system is five credit hours because you spend five hours in class per week for twelve weeks.

I have most of my experience with the quarter system. The typical load for a full-time student is three 5 credit hour classes per quarter, three quarters a year. It's not uncommon to have an additional class that's less than five credit hours, such as a PE class which is often two credit hours, or some kind of orientation to campus that's one credit hour.

That means nine full time classes per calendar year, plus up to something like four less burdensome classes.

Usually, you need to be taking a minimum of twelve credit hours to be classified as full time and if it's over eighteen credit hours, it's classified as an overload and requires permission from the school. 

In my first two years of college at ages 18 and 19, I typically took 15 to 17 credit hours per quarter. Once, I took 20 hours, which was an exhausting overload. Another time, I took 12 hours.

I also took one summer class, and went with a universally required basic course available in summer because there was adequate demand for it. That was the only time I personally ran into an availability issue, but I was futzing around taking what interested me.

I had friends who were pursuing a degree in earnest and they sometimes stressed about availability of the classes they needed. If you want an actual degree, you should find out what classes are required, when and how often they are offered and what their prerequisites are so you can plot out a tentative schedule in advance across multiple years.

If you assume most traditional college students are taking their full 5 credit hours as three per quarter,  three quarters a year, that's nine of those classes annually, not counting any of the smaller classes, some of which (like PE) may be required to graduate. 

Part-time students are often taking two classes a quarter which is eight classes per year, just a little short of what many traditional students are taking. 

These days, many traditional students are taking 5 years to complete a four-year degree, sometimes because they didn't plan it out and couldn't get some requirement they needed until year five.

Last I heard, two classes was also the minimum necessary for certain kinds of federal financial assistance, like Pell grants. 

So with some planning and research, it may be feasible to complete a four-year degree in five years going part time without any need for new special programs aimed at adult learners wanting part-time degree programs.