Are you frustrated with the game?
Cannot reach your desired rank?
Sick of the same scenario every match?
Sick of seeing the same 20 champions every time?
Did you break something after losing an important to you match?
Are you becoming increasingly toxic?
Do you have a chat suspension?
Do you feel like you are not having fun and play only because something is compelling you to feel obligated to play?
#Then TAKE A BREAK!
It is very important for a healthy mental state that you do not spend too much time of your day in League or any other competitive game. Especially if you're a casual player. I know the LCS has brainwashed most of you into thinking that you have to be glued to the game in order to be the best, but please do care for your health and well being.
It is completely fine to take a break from LoL for a month or longer. I would even reccomend uninstalling the game for awhile, just so it does not tempt you. Your acccount and skins are not going anywhere, Riot does not ban for inactivity.
Your skills are not going to go "rusty around the edges". After your break you will actually play alot better because all the toxic feelings of frustration and anger will subside. You will be more focused and you will challenge yourself to improve and build upon what you already know about the game.
You don't have to "quit the game forever" and write a Boards post about it. Just put the game on pause untill you are in a better mindset. Then come back with a better attitude and a healthier mind.
Also, don't take the game too seriously. It's a game, not a 9 to 5 job.
Care for yourself. Care for your health. Take a break. It will only benefit you.
EDIT: I am aware that the title may have been worded incorrectly. What i meant was you should take a 1 month break every few months.