I stopped playing on auto pilot and gained +1000mmr in less than 3 weeks

Yep. I went from 4600 (ancient 5) mmr to 5700 (immortal) in a little less than 3 weeks. I was on a losing streak and decided that I would make all my decisions in the game with a goal in mind. It doesn't matter if the goal is the best choice at the moment, but chances are that even if that is the case, you will still be more focused on the game because you have a goal to achieve. Now, what are these goals? The first thing you have to do right after the picks is to read what your powerspike is and what you need to do to achieve it. For example, you are playing Faceless Void, at minute 0 you already need to develop an idea on how to play the lane according to your support and according to who you are going to play the lane against. And based on this you adapt your skill build and items. There are games where it is better to have the timewalk maximized and in others it is better to have the timelock, there is no single formula for any (or almost any) hero. The decision of how to itemize after the lane phase is also very important, is it better to do madness or straight to the maelstrom? The important thing is that you THINK about your choices and why they are made and play as aggressively as possible, and when I say play aggressively, it's not just about going to fight. Playing aggressive can simply be knowing how to farm in a lane or hitting a tower in a game you're losing. Dota is a mental game, there's nothing wrong with playing for fun, but if your goal is to rank up, avoid playing if you're tired or in a bad mental state, this is VERY important.