What I am talking about is when you are working on a share and you DO hear that the block has been solved. That isn't recorded in rejected shares. It just goes away. Yes on an individual level you might solve the share at at exactly the right time and waste no hashrate. You have to look at the statistical probability, over time, to see that you are wasting it.
You don't 'waste' hashrate if this happens, assuming zero latency. As has been said, you don't 'work towards' finding a share. Your chance of finding a share is independent of the past, it is constant at all times. So there is nothing to 'go away' (this is exactly what is meant by whoever brought up the gambler's fallacy). By your logic, if the average time to find a share were significantly longer than the block time, you would have nearly 0% of your actual hashrate, which isn't the case.
Therefore, I don't see how it would skew the stats in favour of faster miners.
There is no actual partial share, but from a probability standpoint, there is the same effect. If it takes you 30 seconds on average to find a share, and I give you a 30 second time limit to find one, 50% of the time you will, 50% of the time you wont. If i give you 50 seconds to find one, more often than not you will, but there will still be plenty of occasions where it will take longer than 50 seconds and you wont make it.
Its probability. Probability isn't very useful with a sample size of ONE, which is what you keep trying to use as an example. The useful ness of probability becomes greater the greater the sample you use it on.
If the average time to find a share was significantly longer than the block time OF COURSE you would get nearly 0 of your hash rate. Think about that. If it takes you one minute to find a share on average and the block changes every 10 seconds, you have a race condition you are only going to win about 1/12* times.