This was an advice that I read somewhere here and helped me immensely:

Start a PF, DF is a waste of time for most of the part. Each time aim to clear a phase or two. For example first aim to clear out conflags, then progress to divebombs, then snakes, then twisters. It might go faster or slower depending on your group but there are several people stuck on different phases of T5 and for some reason feel awkward about starting PFs. Just go on ahead and do it. I was stuck on this for months and when I decided to *really* put my heart into it I cleared it in 3 PF attempts.