Used to figure all generics were the same thing in a different bottle, honestly. Then my dad got switched on his blood pressure pill and started getting a cough that his doctor said was a known side effect but he never had it on the other maker. That kind of opened my eyes. Fillers and binders really do matter for some people, even if the drug name on the label is the same. As for knowing who makes it, you can ask the pharmacy what maker they have in stock before they fill it, and the bottle usually has the name on the label too.

Read a thing from some old concrete guy about treating your mix like it was produce at a farmers market, keep it out of direct sun or it goes bad on you. He said staging in shade can buy you 40 minutes or more on a hot day, which lines up with what you saw on that slab. Heat pulls the water out of the mix fast, and once that surface skins over you are fighting a losing battle with the float. The part most guys miss is the truck itself, that metal drum just soaks up sun and bakes the load before it even hits the chute. Smart move parking in the shade and working the shaded half first, that is just paying attention to what the mud is telling you.