I might have worded it wrong. If you can correct me, please do. when you have everything powered, you see the iron plates move along the belt yes. what i mean though however, is when you want to build a factory finished before you power it up, you can have an icon showing what resource the belts are transferring. If you've played factorio, remember the "alt mode"? it's kinda like that. you won't have the need to manually go to the belt to see what it transfers
tried to edit it, see if its more understandable now