I'm a bit of a pack rat and therefore want to save everything, but I'm going to have to go through all my old art and see what I want to keep/don't want to keep. I had to move recently and transporting everything was a real pain. I'll probably hang on to all my old sketchbooks, (I love looking at progress,) but I've recently graduated from college so there's a lot of old class drawings and projects that I've accumulated over the years ;A;
I think it's good to save some old stuff so you can compare it to your new stuff to show how far you've developed, or even revisit old drawings later. But if you keep everything, you need a place to put it and it becomes a pain. Digitally however, it doesn't really matter especially if you have a lot of storage space!
I guess semi- fortunately, I've only been drawing for like 5-6 years, so I don't have TOO much build up.