Yeah, that's not the issue. The much easier and cheaper solution is simply to not build the new shit they want. Unfortunately that means they're only being satisfied by the resources you had before, but consume more of it, because each citizen tier is more populous than the last. For example, if you've got Engineers eating Fish, Convenience Food, and Luxury Meals, as they would like, than any one of the three can fall behind without you having to worry too much while you catch it up. If they're only eating Fish and Convenience Food, the first thing they'll do is increase your demand on both. Normally at this point you'd start trying to meet their new needs rather then continuing to increase that population, but if your goal is to achieve a certain number of that population, there's no point. It's faster to just make current infrastructure more robust, but it's hard to maintain with large populations. The idea is to complete the mission without having to invent heavily in a new tier of technology.