All of those hours of practice are merely covering what was already gone over in lecture, only it is largely unguided, and you're not really expected to correct your mistakes and do it right once the assignment is graded and handed back to you.

Once you get into a job, you're constantly revising past mistakes, doing new things and all the while you have coworkers who are helping you- they don't want to wait for you to make a mistake, they want to help you get it right the first time if you need the help.

Uni courses rarely cover real-world knowledge that you will use on the job. Aside from some specialized jobs, most of what they teach you is either too low-level or mostly useful as background knowledge. So many practices aren't covered in college courses- even things as simple as version control have only recently started to become common.

You're going to be learning a lot on the job, and at a decent job what you learn will make what you went through in college pale in comparison.