Even though I was stronger with some exercises than others, I began at PE1/Week 1 for everything.
As the weeks have progressed (week 10 right now), I have found that EVERY exercise is my nemesis; because there isn't a single one with which I haven't at the very least, improved form.
That said; the Arch Body Hold practically reduced me to tears by the 4th set on Monday and it became my 1st failure - got to about 50 secs and just could not hold myself up off the floor any longer. This is going to take me a LONG time to master.