This depends on your situation. I sure had to, but that's because I didn't really focus on college as much as I should have.
Here's how you figure it out. The college I went to required 128 credits to graduate. 128 credits divided by 4 years is 32 credits. So that means to stay on track you have to take 32 credits each year, or 16 per semester. A typical college class is 3 to 4 credits, and realistically, you need to spend two hours studying, reviewing, etc for every hour you spend in class. A three credit class tends to meet around 3 times a week for an hour. So if you have 16 credits, you'll spend 16 hours a week in class, and about 32 hours beyond that studying for tests, reviewing notes, meeting with study groups, or talking with your professor to get help.
That's 48 hours a week. And you're going to want to do stuff while you're in college, like participate in activities, spend time with new friends, explore the city you're in, and more. You may also need to work - not everyone is able to just focus on school full time.
If you fail a class or don't make the minimum grade to move on in your program, you'll have to retake the class.
Worse, if, like me, you decide that what you went to school for wasn't a good fit, you may decide to start over. I ended up taking five years to complete.
You're going to have to find out what works for you. Summer classes are intense because they go twice to three times as fast as the normal ones. For example, a 16 week course can be done in 8 weeks, or even 4, in the summer. You'd go for two hours at a time, for 8 weeks, or maybe even half days every day for 4 weeks. I've done both of those and they're intense, although if you only take one summer course at a time, you aren't dividing your time across multiple courses so you can immerse yourself in the one thing you have to study.
General education classes, like sociology, history, psychology, political science, religious studies, etc are good candidates for summer courses, by the way.
I hope this helps you make a decision that's right for you.
Online college courses give you the freedom to study any time of the day or night. By taking online courses this summer, you can start whenever you want and complete your required college courses at your own pace – allowing you to fit your summer academic goals within the confines of your work, family or social calendar.
You certainly don't have to take summer school courses if you plan out your class schedule accordingly. Many majors can be completed in four years with summers off, and even allow time for a part time job or internship. Even if you do have to take a class or two in the summer, you can always look into flexible options like online courses, independent research projects or internships for course credit. I managed to work almost full time in the summer and take a few online courses, and never had a huge problem managing my time. Online courses let you set your own pace and schedule so you can get to the work at night or on the weekends and still enjoy your summer and relax or travel, and/or have a job.