While not directly targeted, the core gets worked with just about every movement. But other then that every body part\section has a day of work and a day or more of rest.
What I do too.
I am focusing on upper body and core, no leg work at all. I do treadmill for cardio 2x, and hot yoga for cardio 3x.
Every gym day (~5.5 a week) I do 10 sets of 20 reps on the ab machine, I knock them out in ~10 minutes so the heart rate stays up.
One day pull, the next push. Skip a day if I overdo it. I found out the hard way the triceps are busy both days
