The Problem With Metrical Grid Theory

I'm not sure that people speaking a language actually do this kind of calculations when they speak, but it's how things happen. The theory is you have this prosodic hierarchy. And so whichever one happens to line up where you have five levels of prominence all over the exact same syllable, that one is your primary stress. Some languages like English and Russian have lexically determined stress that has to be memorized. So there's definitely something you have to deal with.