> An answer usually contains more information than just that one bit.

That means there is less information in the question "do they have long hair?", not more. Asking "long hair?" and then "woman?" is probably, in most groups, roughly the same as just the first or second question alone. So the second question added much less than one bit of information because the answer is probably "yes". "Long hair" and then "metalhead" is the same, except that the answer to the second question is probably "no".

Yes/no questions on average contain the most information each when they partition the remaining possibilities 50:50. Then each answer gives you exactly one more bit. The closet you get to either a 100:0 or 0:100 yes:no split, the smaller the fraction of a bit you encode in the answer.

"Metalhead?" usually gives you lots of bits of information (probably 4 in an "average" group of 16 containing at least one metalhead) if the answer is "yes", but on average that's outweighed by the very high chance that the answer will be "no". If there are no metalheads or only metalheads, it gives you zero information.

Ah, I flipped it in my head. That happens after 10 years.

In this case, it was often an interesting exercise in bias as well. "Woman?" would usually single out 1-2 persons out of the 15, so it was a terrible question. It was CompSci after all. "Long hair?", lumping women and metal heads into one group would often split it into half and half. That was much better, and then spurred creative thoughts like travel distance, or bus stations.