Stir frying demands a blazing hot wok. I was privileged to eat at Barbara Tropp's China Moon Cafe a couple of times. The open kitchen was an inferno. A good cast iron wok takes a long time to really heat.
Linda C

I've been cooking in woks for more than 40 years, Linda, so am well aware of how hot they should be. But those instructions are self-contradictory.

Until fairly recently, most home woks were carbon steel, not cast iron. I would venture a guess that most of them still are carbon steel. At first, cast iron woks weren't widely available for the home kitchen. Today they are. But most people don't want to put up with the weight for what they see as a limited-use utensil.

Anyway, heat one of those carbon steel woks, empty, over high heat for 5 minutes and if you're lucky the only thing that will happen is it will turn blue.

Yes, cast iron takes a while to heat up. But you don't start cold cast iron over high heat. Then there's the matter of going back and forth between temperature levels. Cast iron doesn't react that quickly (especially with something that's only going to cook 2 minutes in the first place), nor is it necessary, once it comes to temperature, to ever go back to high in the home environment. You just need medium to medium high to maintain the heat you've reached.

Comparing a Chinese restaurant kitchen with a home kitchen is falacious at best. In the restaurant they turn the heat on under the woks at the start of the day, and don't turn it off until closing time. Maybe you cook like that in your kitchen, but I reckon nobody else does. And notice the use of the plural---woks. Any Chinese restaurant worth its soy sauce has a long row of them, constantly in use. That sort of thing doesn't take long to heat up any space.