Sunday is for every trainees free day, or at least that's what I always heard even from my friends from other companies. Most trainees usually spend their free time studying if they are still student, some still go to the company to practice if they feel like they still lack in something and they need to fix it before the monthly evaluations. But on this day you had the opportunity to go ot with friends or visit your family if they lived nearby.
~That was your little glimpse into my Kpop trainee life, I hope you learned something.^^