because it works. my son actually had 2 trampoline accidents where one of his teeth cut way deep into the inside of his lip. we thought it might need stitches, but we used bee's aid on them and they healed with no stitches and no infections! what you're searching for is in a certain type of project, but you don't know exactly which project, searching by working set helps to narrow the scope of the search. please see grouping projects with working sets for more information on working sets. 