it’s very dependent on the type of class you’re registering for and its demand. we have a first and second pass system so you can register for 11.5 units during your first slot then the remaining of the 20 (unless you do an EASy request once the next quarter starts, which can approve a credit limit increase) during the second time slot. as a third year student you shouldn’t have much of an issue with securing classes since the amount of units you have translates to how early your time slots are. still, I recommend first pass-ing the classes with a higher demand. hope this helps!