While I agree that using one size spinner can improve your casting accuracy, you still have to adjust to changes in fishing conditions. Stream level, depth, velocity, width, cover, cloud cover, water temperature, and wind speed are all factors in catching trout, and a successful angler must adapt constantly. I have found that on larger, deeper, or in high water, larger spinners often work better for me. I usually can adjust to a change in lure weight within a few minutes.
Frank is right in that it’s different for every angler. Not everyone likes using the same type of rod, line, and reel, as you can see by reading the “What Are Your Trout Fishing Preferences” post, so it stands to reason that preferences on spinner weight will vary as well.
When I first started fishing with spinners, I read a lot of articles that advocated using size 0 or even 00 spinners. I used them and did catch some trout but had to resort to using split shot with them. Over time I found that spinners that were at least 1/8 oz. with no split shot, and no snap swivel worked best for me. That certainly doesn’t mean that one won’t catch fish using the other methods I mentioned.
It also depends, as Frank said, on your fishing goals or expectations. Do you want to catch a lot of trout, concentrate on catching big trout, or something in between?
You’ve made some spinners of different sizes. I recommend that you try different ones to see what works best for you. That’s the fun part.