How does one become better ?

Hi, i love this game and have played quite a lot (~200h) mostly in multiplayer with friends on casual games. I feel comfortable enough in making some decent network and i would say i’m an intermediate level player. But my question is how does one transition to a master level in terms of network size and efficiency ? I see some videos of dudes making huge ass network the size of the entire map nearly without inefficiencies (not apparent ones at least) with hundreds of trains making stacks each. How ? I can’t make a junction or any high capacity network without it clogging up and some trains loosing money cause of a lack of cargo. I know that some things come with experience, but if there are any ressources online on how to make those big ass network, i would be very grateful