It appears to be very straightforward to me. In calculating your 24 hours of "score-pertinent-on-time" you are only allowed two breaks of at least 30 minutes each. More than two breaks don't count as breaks and do count toward your maximum of 24 hours of on-time.

Another way to look at it: if you take off six hours to sleep, you need not worry as your total time with no other breaks would not exceed 24 hours.

Personally, as I seldom spend more that 15 hours in any one contest, this will not effect me.

73 -- Larry -- W1DYJ