As a disclaimer, most of this could be ignorant and I openly will say I need more defined notions of "how to get better" as a singular player rather than as a student of a coach or part of a well established community of other players.
I have been developing as a SC2 player specifically over a few weeks of the previous months (some weeks really training and seeing massive ladder success, most just playing enough to not atrophy skills). In the first major week of practice I had a very mechanical based regiment (execute this build while dotting the i in every marine you produce and win, fail and you'll probably lose) and the last week I have worked on a very conceptual regiment that has allowed me to "unlock" my mechanical abilities.
So the question rises, what does the average Bronze, Silver, and Gold leaguer need (other than dedicated practice time) to become better as an overall player? There are arguments for both ways.
A very mechanical player will be able to out-macro, out-micro, and out multitask any other player he sees that is below their K+M dexterity levels. However what does the mechanical player need to actually macro, micro, and multitask? Stuff to make, move, and do. As a completely new player to an RTS game mechanics can be the biggest challenge, as even other newbies to the game can simply win because they know how to actually "produce" stuff as soon as it crosses their mind (ala hitting sddd for three drones). As a player develops their ability to actually execute what they know can be the hardest part of the play or make you so overwhelming to your enemy. A terran who can micro two drops against me and have an army ariving on my front door is extremely scary and will almost always win if he gets into that situation.
On the contrary, a very conceptual player may win out with fewer units and poorer control because they can read the opponent well and take advantage of their weaknesses. A lot of terran wait to engage zerg if they see lots of spine crawlers in the natural until they can just skip them alltogether and elevator to the highground. A very mechanical player without knowledge will probably lose (in low league players) because of inherent inability to properly use all the dexterity/mind control he has and do the same things to wear down the opponent which may or may not be successful. This knowledge type play finds weakness in not having the sheer numbers/earlier time of the mechanical player.
Both types of training must exist for a player to get better as a whole and make it to the highest ranks, displayed above. A mechanical player has knowledge to learn on when it is safest to expand (then build on location at soon as he hits 3/400 minerals) and a conceptual player has mechanics to practice so that their advantages aren't taken away (such as microing drops or macroing to the hard-counter unit quickly). Should they be developed separately? At the same time? Finally, How should they be developed?
Starcraft 2 is a very spectator type sport but even watching streams of the absolute best players can be overwhelming to see the mechanics or analyze the decision making when seeing from a caster-perspective (GSL/MLG). TL is a great source for different regiments as well as knowledge. I have referenced it many times for different things such as micro-trainers, new build styles to attempt, and ask for help. There is no EZMODE way to Plat, Dia, Masters but if players are trying to improve from Gold and below the game may prove to be "too much".
My Theory: (Based upon lessons and shared ideology with ohokurwrong
Players actually get better with their mechanics much faster when working toward a conceptual goal of "pressuring" an opponent, gaining map control, and scouting because of the inherent things that need to happen for a timing attack, low unit engagements, and knowing what the opponent does and the opposite applies for A mechanical player gaining knowledge of the game (such as why a timing works/doesn't work in replay analysis, learning micro techniques, and what reactions opponents have based on very mechanical type play). This is almost so true that your primary stress may develop slower than the secondary skills around it.
So the things that should be done to develop as a player:
Switch focus every few days between a mechanical and conceptual development. (IE never miss a worker/get supply blocked for a few days until it is more second nature than before, then work on expansion control or reading an opening). In actively trying to scout better, your multitasking will get better (macro or die!) and in trying to macro better you can understand builds/metagame developments better.
How can I do it?
To be frank, this is something I need to do as well...as a fairly low level player on the TL forum. I've got a lot of conceptual aptitude but my mechanics lack severely. Let's break down concepts first. First is probably watching more pro play overall will help this aspect of your game. Not only will you actively see the meta-game but you will also see how pros react to different builds and developments. If a Zerg goes super fast Hive, start asking all the questions (Why did he do it? How can he do it? Is he safe enough to BL/infestor? What did he see (or not see) in the opponents build? how does he lead up/execute it?). Do that for anything that all the questions aren't snap-knowledge obvious. If you're stuck or don't have the time to constantly watch the pros, a small community can really help and you can analyze your own replays and follow metagame trends from TL or something. On the mechanics side, it is simple reptition and I believe the player needs to decide what is the best way to work on it. As a player who wants to learn caster-micro to help my late-game...I just try to do it in my ladder matches and have it be done so I know how I react live. Rarely do I personally find that micro-trainers worthwhile to train skills unless there is one you'd really like to beef up for whatever reason. Mechanics take a lot of focus to develop and observation of the VODs of pros to see all the "how" questions play out (moving army, pre-concaving, etc).
As a disclaimer, most of this could be ignorant and I openly will say I need more defined notions of "how to get better" as a singular player rather than as a student of a coach or part of a well established community of other players.
I have made a lot of critical success in both departments from Ohohkurwrong (SC2 handle Orange 338) and his training and he is open to take students if you contact him. All of last week I was a silver level player and a little guidence in concepts and knowledge made my mechanics go a lot farther than before. He serves as indirect inspiration for this particular blog as I ponder about what makes players overall---BETTER.