I don't know which is worse, not finding something small in a "busy" area, purchasing a tool or bike part that I already had and forgot, or not seeing what I a looking for that is right in front of me and finding it after several days. All of which are show stoppers. My dad could never find the tool he needed so he bought what he needed. After his passing there were a lot of lost tools found and now there is an excess of them.
Having said that, I think the ops situation is the worst, loosing an original part that is not easily replaced.
I now use a magnet that is ball shaped with a long handle and a release to search the floor. A gift from my sister.
P1030160, on Flickr
Inspired me to get one for the bench.
P1030162, on Flickr