If I have a large amount of fabric to starch, I go ahead and mix up the sta-flo in the sink or bowl and wet the fabric all the way down. I wring out what liquid I can and then let the fabric set so it soaks all the way into the fibers (at least 15 minutes). If it drys out that is fine too as a little spritz of water from the iron and it's good to go.
I might be showing my age but I can remember my Mom wetting the pillowcases and handkerchiefs and rolling them up then putting them into the frig so they didn't mildew. We'd pull them out and iron a few at a time over the day until it was time to start all over. I also remember getting upset with my StepDad and spraying each "fold" of his handkerchief with starch....they were so stiff "nothing" would stick to it when he sneezed or blew his nose, lol...bless the guy because he never said
a word or cracked a smile when he used that batch of them.