Wait, That Was 1/2 a Second!

So I was reading the back of some cooking spray last night as I was making dinner (waffles). One serving is 1/3 second spray. And there are about 743 servings per can.

How did they find this out? I just imagine a three people standing there, one tallying sprays the other timing them and the third spray. Think of all the hijinks that would involve. And all the floundering when the sprayer sprayed something other than 1/3 of a second.