If you can't find a particular shot, nobody will go out and shoot for 1 sale.

Doesn't make any business sense. So, my advice is to hire your own crew.

Horsespuckey! If someone contacted me for, or I became aware of a need for a shot which I was able to make, but had not yet done, and I was able to then use that clip for stock later, the potential client is A) Giving me an idea for a concept I had not yet noticed or realised, and B) Paying me for the shot, which, in the case of shooting for stock, is better odds than most shots.

But that's hiring me ... and the gear I have ... not hiring a crew, rentals, travel time, etc. In THAT case, yes, hire your own crew.

Often though, as expressed by a person I was working for who could not find a shot, they are either asking for the shot improperly (not using the search correctly) or simply asking people if they know of a shot to specifically suit their needs in case the search results, which are biased, are not giving the result they need. Asking a group of random humans CAN be more effective than asking a stupid search robot!

Yes