It is easier coding-wise to have it only trigger the first item in the queue but when I play Evolve I almost always have it set to do anything in the queue and I use the queue to build houses and stuff, rather than clicking it whenever it is buildable. To encourage this behavior, rather than using the massive dropdowns have it so you can use a hotkey to click and add things to the queue.
You will always want to build the basic things because there is a point where the cost creep makes the more advanced things less efficient than the basic things.