They're just all different, sorry. Some really do need a bit of a steep. As a general rule, fruits often don't need a ton of steeping while bakery, tobaccos, sometimes chocoolates need more.
Also, perhaps I am just a tinkerer, but like, I find it pretty rare to find a one shot I can't improve slightly, at least for me.
I think they can be a great thing to have on hand, especially if you like the one shot, you know you don't have a ton of time for mixing and etc.
Anna