The speed improvements calculations seem weird to me. Shouldn't one build done in 178s instead of 304s be 70% faster instead of 42% faster? (you can do 1.7 of build using the old amount of time)
Both are true statements, however people generally like to discuss how much improved the new releases are versus how much worse the old ones are.
Fun fact, it's important to understand that relationship in other areas as well like the stock market; if your holdings lose 50% of their value, they then need to increase by 100% for you to be back neutral :)