How much time should I actively spend with my rats?

Hi everyone. I have two female rats, my first ones, and they are 3 months old. They have free roam for about 12–15 hours a day, and I’m in the same room with them the whole time. They have plenty of toys, lots of boxes, paper, balls, etc. About once a month I rearrange everything so they don’t get bored.

Out of all those hours, they’re awake for less than 6. I tried training them and bonding with treats, but they don’t seem very interested, so I ended up just interacting with them naturally playing with them when they jump on me, run over me or try to steal something from my desk.

My question is: are they comfortable if I spend so little direct one-on-one time actively playing with them? Should I be picking them up and engaging with them more intentionally, or is it okay to just leave things as they are?