Training Mode Suggestion

I was just wondering if there could be a permanent "champion training mode" for us people in the league. Some times, I just want to practice doing a certain move on a champion and not wait for the long cooldowns. For example,I play a lot of lee sin. And I would like to practice more of his skill shots and combos. Maybe adding a new map with immortal objects that could be either stationary or moving can help a lot to me. It is very time-consuming when you are in custom games with a few bots just for training. Also, trying to practice with URF is quite difficult when the AIs have access to the effects as well. I apologize if this sounds selfish, but please consider this thought. Thank you.