During my time with Cassette (wearecassette.com) I was primarily tasked with optimising Turbosquid assets, which were far too heavy in poly count in order to run on our targeted platform. This being VR.
Though I have not provided all the assets that I worked on, the ones present are a reflection of how well I was able to take the asset to a game ready state. In most cases (if not all) I was able to reduce it down below 10% of its original value.
As it was in VR, I removed the necessary amount of geometry that would not be seen due to restricted movement for the user. That is why is some cases, the optimised version may be missing additional objects i.e. mobile unit does not have storage hanging from its side.