How playing different roles can help you learn more
Now we all know that learning a few champs in every role is a must have for ranked because you don't want to end up in a role you can't play well in a game, but there is one other reason that makes learning each role more extensively a good decision. That reason is that each role focuses on a few aspects of the game more than the other ones do.
Here is a list of each aspect each role covers quite thoroughly. please note that most explanations only cover and that everyones personal experiences/ individual games will vary greatly.
Top Lane
The main things top lane deals with are csing and trading because frankly, top lane is very cutoff for most of the early game. This results in you really needing be be able to handle yourself without assistance from other lanes. Top lane is typically the least likely to get ganked because of how far away it is from dragon and because the carry roles are typically found in bot or mid lane, while more tanky roles are found in top. Csing and trading well become especially important when you are unlikely to receive and outside interference for a good chunk of the early game. Top laners generally need to be able to win their lanes with or without help and as someone who played a lot of top, especially earlier on when learning league, I have become a much more independent player because of it.
Depending on the situation top lane is also a decent place to learn about roaming. Here you will probably run teleport, and if you are winning lane and keeping the opponent shoved under tower, roaming is a good way to make good use of your time and break away from the isolation of top.
Mid lane
In mid lane I find that you learn a lot about watching your opponent. With the amount of burst found in mid lane things can snowball very rapidly. As such playing mid can help you focus on watching your opponent. Keeping track of things like mana, health, and abilities can easily result in you grabbing a kill that leads you to victory. Longer range mid laners also are good for learning about poke and sieging towers
You also learn a lot about roaming while playing mid. Probably even more than when you play top. This is because you have 2 options for roaming in mid. Mid laners also have the damage to very easily pick up kills in a gank.
ADC
Adcs also have to be good at csing and trading. This is because they are vulnerable and very gold reliant so these 2 skills are important for getting ahead in lane. Adcs also learn some more unique adc skills like kiting, but applies in fewer other places. Of corse as you are in a duo lane learning to work with your support also helps you learn to work with your team in general.
Support
As someone who is dedicated to helping the adc supports learn a lot about peeling. Depending on the type of support there is also a lot of practice with initiating or poking. Supports also learn a lot about watching opponents and map awareness as they don't have to cs and can focus more on whats going on around the map. Of course supports also learn about warding because even though everyone is supposed to help out we can all admit that supports ward the most.
Jungling
Jungling teaches you a crap ton of stuff because it is so different from every other role. Most of it is also pretty much unique to junglers, but like supports junglers need to learn warding, map awareness, and how to work with a team in order to do their jobs right
If you have any more specific aspects of the game that you think should be added please post them. Also if you disagree with anything please tell why. As you can probably tell some of these sections are a bit shorter than others because I haven't played the role as much. (though jungling will proably stay short because most of what you learn while jungling is kinda specific to jungling given how different it is from the other roles).