Manually adding exercises to Training Journey Sessions

Hi Community,

I started with working out about two months ago.
I hope this is the correct channel to ask such questions.

Finished the first Journey “Fit for Life” and now I am in the first week of “Hybrid Strength”.
My Goal is to become overall fitter and gain muscles.

But I am a bit lost sometimes with the Training Journeys and their choosing of workouts.
Right now I am working out four days a week (Mo, We, Fr, Sa).
This Week I had a Full-Body Workout on Monday.
On Wednesday (today) it is Core (Legs and Abs)
Friday is another Core-Day
Saturday is Abs only.
So I would not train Upper Body (Arms, Shoulders, Back, Chest) for a whole week.
Does this make sense?
Right now I am adding Pushups, Pullups and stuff manually if I see I am missing Upper Body for more than three days in my Freeletics Journey, I am also adding Cooldown/Stretching for those areas to the suggested Cooldown… But am I supposed to do this? Should I just rely on the Journey that they do everything right?