Competency based programs - can you do more than one class at a time?

[suzycupcake]

Hi all - 

I'm still unclear as to how the competency based programs work - can you bounce around and do a little of this class and a little of that class? Sometimes when subjects are tough, I like to bounce around and do something else for a bit and then come back to the difficult thing to tackle it again later. 

Do these programs allow that or do you have to only do one class at a time?