I'm curious why what you would think would be normal choices disappear out of your build choices regularly. For instance, I may not see a barracks as a choice for ages, then suddenly it pops up for a turn or three and is gone again. Same with grocery, bank, etc. They'll just disappear for a while, and later I'll have a strange window of opportunity to choose them. Why would a choice ever disappear, especially if it's not outdated?