Ever wonder where builds come from? Why is 14gas/14pool considered “standard” in ZvP? What makes 15hatch16pool better than, say, 13h/19p, or some other arbitrary number?
People play thousands and thousands of games of SC2 every day, and the way that builds are optimized are by trying to cut as many corners as possible, while still retaining the “key” element of the build you had in mind.
For example, in 14g/14p, you want to get 4 lings out to destroy the Protoss pylon so you can expand immediately after. You also want to start ling speed as soon as the pool finishes so you can retain map control with your lings to prevent the Protoss from laying down any pylons in proximity to your base (“proxy” pylons).
So there are two “key” elements to this build – starting ling speed as soon as the pool finishes, and getting out 4 zergling to clear any pylons built to prevent you from expanding. For the purposes of these two ideas, the build is pretty much perfect. If you did 12g/12p, you would have earlier lings, and you could start your speed as soon as your pool finished, but you would have a large delay between when your 4 lings come out and when you can expand. Hence, you could have instead waited longer to put the pool down, gathered more resources, and expanded later. If you build your gas on 17 and your pool on 17, you’ll find yourself with a large amount of resources that you’re unable to spend for quite a while.
Not every “build” is perfect, though. Builds can be tweaked in two ways – either by adjusting timings to match your “key elements” that you want your build to achieve, or by adjusting the key elements themselves. For example, with the 14g/14p build, perhaps you decide that you only want speed to counter 4gate, but you don’t feel like you need it initially because you’d rather have the extra resources to build your economy faster. You would find out via replays (or customing with a friend) that warpgate tech finishes ~6:30/7:00, then plan your build out so that you would have ling speed finished at, say, 6:15, just to be safe. So with your timings, maybe you can afford to put down your pool at 13 to clear the pylon in your natural, then expand, then take the gas afterward. So your “modified” 14g/14p would turn into something like 13p/15queen/18hatchery/17gas, or something of the sort (I’ve never actually tested these numbers before, careful!).
Experiment, make new builds, have fun. Just be “smart” about it! New builds don’t come from people randomly trying stuff, they come from people attempting to achieve very specific goals, and then modifying their builds accordingly!