There might be things harder than trying to work in an assembly where all the parts are named by their part number, but I can't think of any off the top of my head. Trying to find a particular item in a sea of similar names is a terrible process of trial and error - or you have to plan ahead and keep a list of part numbers (along with their description in human language) on a pad of paper next to you.

RMB click the assembly icon and choose 'show parts description' from the context sensitive menu. This will show the parts description, from custom properties, next to the part number on the feature tree. Now its easy to find your 'top housing', 'frame', or whatever in the tree. Extra points go to SW for allowing us to easily add the description at the time we save a part, instead of having to go all the way to custom properties!

(BTW - I know this isn't much of a tip... anyone who read the 'what's new' manual should have picked this one up. The thing is that out of ten people I've talked to, all ten did not know it existed, and were very pleased to learn it.)