These posts made me smile as I, too, am from the old days and still do things the same way sometimes. Depending on what state I am in, sometimes it can be difficult to find the powdered starch or bluing. Cornstarch does work too. Whenever mixing the powdered variety, yes, you have to keep shaking or stirring it. Otherwise you will have a nice "glop" in the bottom of your bottle.
Even when using the liquid Sta Flo, I shake often. If using the Niagara, or other brand, of spray starch, I often shake it and starch the back side, waiting a moment or two for it to soak in and smoothing it out with my hand. This reduces the flakiness and shine and evens out the starch.
I just mentioned to my son the other day that I would love a glass pop bottle and the old sprinkler top that I used to have. He handed me a tiny coke bottle salt shaker and said, "Here you are." That brought a laugh to both of us.