How often do you move in the US Army?

Yes, MOS does matter, because they have to have a place to put you. as a 42A your specialty could be used anywhere. There are a lot of variables as to how often soldiers typically move, so an actual statistic would be hard to give. However, a good rule of thumb would be every 3-4 years on average. Keep in mind though, I have seen people stay as short as 6 months or as long as 6 years.