Shops come in all shapes and sizes. Ya do with what ya got. My shop is on the concrete apron in front of a two-car garage. That means, of course, that I have to roll my big machines outside when I want to use them and put them away when I'm done. If I had room to build a shop, I think 20x30 would be the minimum size I'd consider.
Ideally, we'd all have the the ability to handle a full sheet of plywood on our table saws. However, that just is not reality for many of us. In my own case, I don't have large infeed or outfeed tables that can handle a full sheet. Plus, I'm getting older and it's difficult for me to handle one alone. For that reason, I always rough cut large plywood pieces then trim them to final dimensions on the table saw. I do that with a couple saw horses, some 2x4s, a straightedge and my circular saw. It's a lot easier to handle an 8 lb. saw than it is a 60 lb. sheet of ply.
The procedure only slows me down a little and my "rough cuts" are pretty accurate. I usually don't have to trim very much so my waste is minimal.
There are mobile bases available for table saws that permit rotating them 90 degrees...or rolling them from place to place like I do. The caveat here is that your infeed and outfeed tables also have to be on casters so they can be repositioned with the machine. That's the only way you'd be able to handle 4x8 plywood sheets by yourself.