When I was at university, some of my classmates were admitted right after high school, others failed, waited for one year while having a job, and then applied again. The difference between those who had one year of work experience and those who had none was profound; the former were adults, and the latter were kids; it was as if they had five years of age difference, not only one.

I wouldn't underestimate the professors though. Doing research (that is their actual work; teaching is just a hobby) can be hard work.