Good question!
Agree with jaquet that it's okay to practice a section F to iron out the technical challenges, but if you do this all the time you're setting up a problem - you'll have to relearn it at the dynamic indicated. How you handle the arm/hand weight, the wrist movement, changes based on dynamic level, plus you're building muscle memory on the repetitions, so practice the section p or pp as much as f.
The finer elements of a piece - dynamics, pedal - have to be practiced with intention. Students often think that those can be handled in the moment once the notes are learned but that kind of unpreparedness shows in the performance. You come to you're pp section and find you're playing it MF instead - why? because you practiced it F, and you can't take it down 3 notches at run time.
BTW, thanks for posting the YT tutorials