I have won games against players with 6 times my APM and 4 times my metal income by winning decisive battles and bulldozing their main base. After doing this so many times I'm starting to think nobody really considers terrain pieces in their tactics beyond obvious choke points and the hilarious effectiveness of craters. If your army would normally be outranged or outgunned by the enemy army a good way to maximize your units potential is to have them bunch up behind csg or around a corner on a metal planet. My unit compositions favour these tactics as I go t2 later and have a lot of sparks and combat fabbers in my inferno/ant blob. It gets hard countered by slammers and levelers in open combat, but if the enemy willingly engages in close range fights (and boy do they) I can rip them apart. As you can see from my very high quality chart, a corner or even a singular mountain can be used almost as effectively as a real choke point if your enemy isn't paying attention (and they aren't which is why I'm writing this). Even if they notice your plan, you force them to reposition, which is a good thing to make your enemy do as often as you can in my experience.
honestly I kind of think PAs terrain needs to be more visibly separate from the ground, especially on ice and desert planets. A darkened strip air brushed just off of ground level should work wonders in terms of people actually noticing these things.
