[fadetree]

Talking about randomness is weird and confusing, because we actually don't know what it is. If we did know, then it wouldn't be random. We know what it ought to look like from a statistical sense, so we can say that something doesn't SEEM random, but that can change over the length of sequence you are looking at. A sequence of 1 is not random at all. A sequence of 10 really can't be said to be random. Sequences of hundreds is where you start to get statistical grasp, but all you can ever say is that it 'seems' random. Then, when you start talking about repeating subpatterns that seem nonrandom, such as the skillups pattern, the math gets deep.
So that's some philosophical B.S., but anyway the pattern I have seen in skillups and other things over the 20 years that I have been playing have got to not be random. I feel it in my bones there's something else going on in the machinery besides a D100 roll. Especially in skillups, it really feels to me like there's some kind of state being saved and used or weighting based on how many times you have tried since your last skillup...and the math is not smooth (hi there, hell levels) so you get a cluster of skillups at the end of the sequence instead of a smooth distribution.