William,
I did not attempt to adapt to 4x30, but my husband and I both tried 6x30, and our experience was that days 4-6 were the most challenging. If you decide to give it another try, get caught up on you sleep debt first. Also know that very few people succeed at adapting to 4x30 because it's hard! You might consider 6x30 (or 6x20, 6x25, or whatever nap length works best for you). Another option if what you're looking for is extra hours and a more even energy level is 3 hours at night and 3-4 naps during the day.
Lots of information at
Google Groups - Polyphasic Sleep.
Good luck!