Sometimes, you just make mistakes. For example, you may be very very careful with all you measurements only to discover, once you have all the parts cut, that you were actually measuring the wrong thing.
That’s happened to me a number of times. For example, I was making a chest of drawers. I had the body of it all assembled and knew the proper drawer sizes from my little scrawled plan and also from the carcass itself. So, I cut all the fronts, sides, backs. I cut a dado in the sides and fronts, cut the backs so I could staple the drawer bottom – I’m sure you are all aware how such a drawer is made. Then I assembled those parts and measured for the bottoms. I cut all the pieces out of 1/4 inch plywood and was about to start sliding them in when I noticed I had measured between the sides and not made the bottoms wide enough to slip into the dado.

After congratulating myself on a job well done, I thought I could use those pieces for something else, so I cut some more. Luckily, I had enough plywood left to finish it. So, I slid the first piece of plywood into the drawer dados and was relieved to find it fit.
I like to confirm the fit of my drawers in the body of the dresser before fixing the bottom in position. I find that making the drawer square may not actually ensure that the drawer sits correctly in the finished product, since I may have made a slight error cutting those parts or perhaps some other magical event occurred to make things a little out of square. Everyone makes mistakes, after all.
So, I took the first drawer and slid it into the body of the dresser. Or, rather, I didn’t slide it into the body of the dresser, because it was too wide. It was too wide by roughly twice the thickness of a drawer side and I knew I had made the back and front (to which the sides were butt-jointed with glue and nails) the wrong size.

I was very pleased to see that I had done that, especially after making the drawer-bottoms twice. So, I merrily knocked apart the drawers. After an hour of searching the mess of a workshop, I found pliers (just as I was about to go purchase another) and pulled the nails. Several of those snapped off as I tried to pull them and I realized I never needed to actually pull the nails at all. I should have just bent them until they broke off. But it’s always good to know where your pliers are, even if you only use them once every two years. I thought it was truly quite lucky, I had also found a box of new pencils and a caulking gun. Unfortunately, the tube in the gun had had silicone squeeze out the back end over the plunger and so was very permanently stuck in there. I decided, however, that I might be able to recover it after I threw everything in a fire.

Some of the wood was damaged when I knocked the sides off. I had to make two new side pieces. Unfortunately, I had no more stock so had to go buy more. Luckily, the store where I could buy the material was only a 40 minute drive away. And I was only halfway back when I remembered that I was also almost out of air-gun nails.
Determined that the manufacture of six drawers should not take more than a day, I forced myself to finish them. I glued and nailed the parts together and then tried a drawer bottom. I quickly realized that none of the pieces fit although the first set I cut could have been nailed onto the bottom, since they were the same width. I was very happy to realize that I had truly wasted a lot of material and time. Nothing is quite as satisfying as doing something you love not once, not twice, but three times.
After recutting the original drawer bottoms, I gleefully slid the first one in the drawer and once again put the drawer in the chest.

The design of the chest was simple. It was framing to hold up the drawers and a face-frame against which drawer fronts should stop. The finished fronts were to be fastened to the fronts of the drawers I had spent the day incorrectly making. That meant that, when the drawer without the finished front slid into the chest, it should come flush with the face frame.

It was sticking out 3/4 of an inch. The thickness of the finished front. I had measured the length of the drawer sides based on the dimensions from my scribbled sketch, which only showed the dimensions of the drawer with the front attached.

Sometimes, you just have to pretend a day never happened.