Anyone experienced with Montessori mobiles. I have made them all, but can I not put one up in each room or is there a reason for one at a time, please advise?

Yes, they're meant for one at a time, and they're each for specific points in development. This post explains it pretty well, but there are a ton of online resources that fully explain each mobile's importance for its timeframe. https://montessoriedited.com/timeline/

Thanks this is really helpful wish I got them sooner