My initial prepping was a bunch of canned goods in 2009. I'm going to go through my stuff in January and toss stuff that is way past expiration and replace it with the freeze dried equivalent. After my initial prepping I did the long term stuff so I do have a lot of that, but I need to clean up my space for more.
I need to make sure that I have all of my bases covered and probably go through my inventory to see if anything is out of date or needs improvement.
I remodeled an old closet this past summer and made it into a pantry. I have saved a lot of money my doing that. I have two teenage boys and found cans of Chef Boy R Dee for .16 a can. I ended up buying close to 100. I doubt I have half that now.
I would suggest treating the stuff past expiration as research. Open it, and see what it smells like. Other than fish (tuna, sardines, etc), if it smells good, it won't harm you. I have been eating expired canned fruit quarterly for several years to see how long it tastes good, and it is fine even three years past date. The dates are a "best by" not a "toxic after", and, for example, expired pineapple has a slight metallic taste but it's only noticeable if pointed out.
Don't worry about eating expired tuna by mistake. I opened one of those a year past expiration, and no one could mistakenly eat it!