Can I use slot shelving in a wooden shed?
So, from the comments, I assume you mean "slot shelving" to be shelf standards like this:


If this is what you mean, then you should be able to use them, and are quite handy for adjusting the spacing. Biggest issue here is getting the proper ones for the weight of the shelves. More standards (the upright slotted bar) you have will allow for better weight management. Using a double slot standard, and you have better weight capability also. Now, depending on the mounting method, the standards used, the brackets, and the shelf materials, you will be able to determine the weight you can add. The components will list the max weight. But be sure you add the weight of the brackets and shelf material. If it says 100lbs, and the brackets are 1lb and the material is 5lb, and you have 2 standards, 2 brackets and 1 shelf, then you have a limit of 93lbs per shelf. Just a simple example.

Now, building your won from 2x4 studs and attaching to the framework studs of the building, would in essence be the same thing, but would increase the weight of the shelving system, reducing how much weight the shelves can hold.

Your best bet, would be to build free-standing shelves as you are only limited by materials you use to build them, you can even build them to have movable shelves with slots and pins, but this would change the weight limit. This method would have no weight bearing on the structure.

So, in closing, you could you any of the 3 methods you have mentioned. I have used the slotted shelf standards like pictured in my new pantry so that I can adjust the shelves as needed. In my shed I have free standing shelves that I got free from a business tossing out old shelving systems. My garage has a combination of free standing plastic shelf systems, as well as the slotted standard shelf systems, because I was cheap and used what I had from various other projects. I even have some shelves that are mounted to decorative shelf brackets. That is also an option for you.

Not finding info on shelves in a shed is not an issue, because every shed is built differently. Plastic, metal, wood, lean-to, free-standing, attached or detached. In my case it is an attached with one wall of the shed being the rear wall of the garage.