First of all, it's not random most of the time, and by not random, I mean that most people have some sort of specific style of placing notes that they usually resort to. You could say that currently, jumps are thrown around carelessly, but the flow and the positioning of the jumps are generally catered to one's aesthetic needs, and the usage of larger spacing and smaller spacing (jumps or not) follow the music.
In terms of every map being different, I would disagree that most animu maps are almost all the same in terms of flow and playstyle. I would only give "putting a twist" on maps mapped by specific people, such as Skystar (Amamiya Yuko), Colin Hou, fanzhen, RLC, tsuka, AngelHoney, DJPop, Fear (soulfear), Hollow Wings, and probably a few more. The reason being that when you play one of their maps, you pretty much know it's probably made by them, because they actually have a very specific and special way of mapping that other people aren't able to achieve. Playing all the animu maps, you really can't tell who mapped what. Nothing wrong with going along the bandwagon and mapping that way, but you won't make yourself super well known unless you truly stand out with something different. I mean that's kind of why the skystar controversy is happening right now, but personally his style makes the maps more fun to play than other ones.
"Placing random notes and making it flow" is not a method and will get you nowhere, because it is not as random as you think. It looks random, but it is placed so that it's not aesthetically displeasing. And trust me there are tons more ways to place notes in ugly ways than there are in good ways (even though there are many many ways to do it in a aesthetic way too.) idk how much you've mapped, but you probably will understand, if you haven't already, when you try to map something.
And no there is no way to learn, you can absorb some of other people's ideas and styles, but you won't truly be able to imitate it. In my latest map, I was trying to absorb some skystar to be honest into it, but it's not like I can say that I have successfully copied him and his method. I still have my own take and method on it, but I added some special elements to it.