I do the same, sleep when I'm tired and have the problem of sometimes having to match my sleep/day to being awake at specific times for one off things and sometimes that throws me off productivity. I have also found that I too in general do 24-30 hour days, I'd say the average is 18 hours awake and 10 hours asleep, although I've done as much as 34 awake and 16 asleep.

I've been doing this for over a year now and I think it's hugely beneficial for me, although within a month I'm moving to working from an office so I'll be trying standard 9 - 5 (I think, unless I'm allowed freedom!) so it will be interesting to compare. Personally I think structure is good for me, although the freedom is great I can find myself wasting 2 days without doing anything productive... definitely something everyone should try anyway