I'm not a fan of a man whose name might be William Allen. It seems that he patented the torture device known as the Allen wrench in the early 1900s. In the past few days I've taken apart a king size bed and a large five-shelf bookshelf with an Allen wrench. Actually it was two Allen wrenches because the hex screws were different sizes.
And then I put both of those pieces of furniture back together. The end of my index finger is sore from providing pressure to turn the Allen wrench. I used the wrenches in both the horizontal and vertical orientations, depending on the location and the amount of pressure needed to insert or remove a screw.
The lesson I learned is that you should check your build-it-yourself furniture once a year because some of the screws on the bed were loose. And I put it together a little over a year ago.