(It may be easier just to skip down to the last paragraph if you don't want to read my long ranting post.)
I work in a job where our performance is largely based on numbers. I work in a factory that produces styrofoam cups and bowls mainly. If I have a line that includes 8 machines, they expect a certain number of boxes to be made. We write down if a machine isn't working and things like that. They are supposed to take that into consideration. But, still at the end of the month, I may have met the "goal" 10 times out of 20. I so my best most of the time. But honestly there are things that eat up production that would be crazy to document. I will try to explain. Sometimes we have a line of 6 or 8 machines and they send the cups down the conveyor. Sometimes some of those are sent to a print machine (that someone else operates). Sometimes all of them are put into boxes that we tape up and stack up, etc. Then while we are doing that we work what is called a "handpacker" where we have to put the plastic sleeve on a set of cups and seal it and box it up. This sometimes requires continual work (especially the machines that we have to nest the cups or lids together manually).

Whoa, just a break here-- I may be losing people because I am trying to describe something that many have never done. Oh well, I will go on.
Well, let's say that I am continually working on this handpacker, BUT lo and behold the line decides to act up and I have to go clean up a mess and reset the machine. Then I go back to the handpacker, BUT the machine that pushes the cups in the box acts up. I get the box out, unsleeve the damaged cups (that were crushed), reset the machine and go back to the handpacker. Well, a minute later a box is done. I go and tape it up. I go back to the handpacker...... and so on.
Yesterday, I had a line with 7 machines that worked and I had to turn on and off adjusting to how fast print was taking the cups. And the handpacker was lids which we have to gather together in sets of 50, sleeve them, seal them and box them (10 sleeves per box). The "standard" is 49 in a shift. The only time I got near that (47) was when the line ran near perfect. But at halfway throught the shift I only had 10 done. But, I can't document the various things that happen. There isn't enough room on the paper and the time it would take up would be another time waster. Anyway, you get my point. This is more of a rant.
But the heart of this post is that ridiculous statement "No excuses." I know that excuses can sometimes be a way of skirting responsibility, but .... sometimes there are valid reasons why things are not going according to plan.
If I bored you I am sorry.