Terminology Check - a hit is where the index made a match with a URL or something on a web page. In general, a hit says I matched the word that you gave me with something. The pointer to that something is then returned to the calling program or user.
Most indexes operate on first come first serve.
This means that if a match is made in 50 web places those 50 web places will be returned. If there is a cap on the number of hits returned, let's say 40 for example, then the first 40 responses will be returned. You don't get to see those last 10 hits- period. Of course you can raise the number of hits to look at, but who wants to wade through 45 pointers to find what you want. Admittedly you have saved hours of indescriminate searching, but you still have an hour or two to find what you want if it is in the 44th pointer.