It’s not a waste of resources though, it’s basically what Jared said, MVC. Coming from web development it’s a technique that I apply to many things. There’s no point in always updating variables at every tick when they can just be updated when they are changed. Additionally, there’s no point of always having data loaded in the background if it’s not necessary. The inventory data is loaded instantaneously anyway, it’s not like it puts a big burden. Small games probably won’t ever notice a difference but I think that this is the better practice to follow because it’s a “use resources when you really need it” rather than an always-on thing.
For things that might require a lot of computation power or has a lot of data to load, make the game show a load icon as it is reading the file(s) / rendering or implement some type of animation to make the player feel like they’re not waiting. It’s better than having an overhead of 2gb of just menu data or something 