Personally i think that if you are trying to emulate a build then you should do it properly no matter your level, otherwise you will miss the point of the build and wont learn as much. If you make mistakes and lose...just try again? It's not as if losing means anything at all, and if you are interested enough in the game to want to learn 'good' builds then a few losses arent going to put you off playing.
I've always found that i learn way more from my losses (frustrating as they are sometimes) than my wins anyway

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To be honest, I would argue that at anything lower than gold/platinum level, the best thing to worry about is basic mechanics. The advice you give there is exactly what i would say to a platinum player who is trying to really refine their understanding of what they can do given the restrictions of their current income.
Any lower and the best thing I would say is just play the game, learn what the units can do, learn what works well. e.g. why protoss likes to get observers against terran as a simple example. Keep building workers, don't get supply blocked and always build units (bar zerg), keeping your money low.
There's a rhythm to each race in their production cycles, and learning that routine is fundamental to learning macro. The most basic example of this is spawning larva. If you're not on top of it, then what you can do is going to look very strange compared to a top player. You'll end up with huge amounts of money banked, and seemingly no way to deal with it. So it makes sense to add more hatcheries every single game right? No, it makes sense to improve those basic mechanics with every single game! But that doesnt mean that when you're in the game, you should only stick to two hatcheries because Idra or Moonglade or whoever did it.
Similarly, if you're not constantly producing out of warp gates, then it may make sense to add more gateways to bring that number down. What RobHu's talking about is an improvement out of game, and yes, is the most important improvement in the long run.
I think of myself as passably alright at the fundamentals of this game, and I'll sometimes end up with far more structures than i should do. Playing as protoss, I did a 6 gate + colossus push off of two bases while taking a third against nex20 the other day. I shouldnt have been able to afford that, and that shows a mechanical problem when on two bases. But I still played in a way that kept my money low. As long as I recognise the faults in my play, I know I can improve those fundamental aspects to my play later on in the game, and that I hope is what will allow me to progress to master's league (although maybe people will just keep 4 gating me so i have an easy ride to masters

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As a player learns the fundamental mechanics better, then they will find, as you say, that they can't produce out of 4 warp gates off of one base and expect to continue building probes and pylons properly. That I feel is the transition to having a basic understanding of the game.
That's also why I'm a bit wary of emulating builds from pro players at lower levels. Some builds that people do, especially someone like Idra, will rely on the most subtle and refined timings and mechanics. A great example I feel is iehoic's famous hellion/banshee TvT style. That is such a subtle and micro dependent build, that it's very difficult to make work properly without good fundamentals. I've seen lower level players attempt it, and they don't have issues because they don't understand the build. It's the lack of fundamentals which break them down, and leave them vulnerable to a very standard TvT style.
That doesnt mean you cant emulate the basic style of a player. See adelscott building lots of gateway units and smacking the opponent in the face until they die? Great! Do that! You can look at how he stays alive and emulate that. See Idra building 3 bases worth of drones and annihilating his opponent? Great, try that! But I don't think it's a good idea to take it any further than that depth until the basics are there.
God I'm uselessly ranting on basic stuff again. This is why i'm going to fail my exams this year!
