Call me a relentless optimist, but I feel the same. It was quite intuitive (for me at least) from the outset to to say I've got four patterns per part...to say to myself, OK, I've got a new pattern here, I can compose up to four variations on it. It means I can compose fills and fades, as Thomas mentions. Or create a 16-bar loop with pattern chain, for example, and only dedicate one "kit" (part) to doing it.

But it took me a long time to find the best workflow for me. part1 = pattern1, part2= pattern 5, part3= pattern 9, part4 = pattern 13,

I'm not into Parts my self personally, but I understand the concept...

Easy tip for Parts / Song usage: (maybe)

Assign the same samples (lets assume just percussion loops) like this: (in Pattern A01)

Part 1 Track 5 = Part 2 Track 5 Part 2 Track 6 = Part 3 Track 6 Part 3 Track 7 = Part 4 Track 7 Part 4 Track 2 = Next Pattern Part 1 Track 2 etc (Everything else, use what ever you feel...)

Pattern A01, Part 01 is your first song Pattern A01, Part 02 is your second song Pattern A01, Part 03 is your third song Pattern A01, Part 04 is your fourth song Pattern A02, Part 01 is your fifth song

Then try jamming around for a bit, then when you want to segue from your first track to your second track, work through and mute everything apart from Track 5. Then switch parts from Part 01 to Part 02... you'll have the same loop playing and will segue between songs effortlessly

Build up song 2 as required, jam, then when you want to segue from your second track to your third track, then strip it back down to only Track 6. Then switch parts from Part 02 to Part 03.