I may be misunderstanding how it's supposed to work, but I used crystals to buy myself an extra build queue for a week. I've been playing for less than a week, so it should still apply. However, when I build multiple items, they always follow one another: i.e. the second item doesn't begin building until after the first one is finished, rather than building in parallel. (This is for my colony, Spin).

I don't know if this is how multiple queues were designed, but if it is, they really aren't very useful, especially early in the game. They seem to save just a few seconds or minutes per build, rather than letting me build one project that takes an hour or more in one queue, and multiple, little projects (like resources mines) in others.