I've been in academics for past 6 years. For the first four years I was doing research in Fluid mechanics. Then I moved to work in Physical chemistry. After such a transition I find that the impact of my current work and the speed at which I get new, exciting results far exceed the time I did research in Fluids. However, I tend to log less hours now compared to past.
My reason is that certain fields are far more young, where all your efforts turn fruitful. But how can one find such young and impactful fields for building up a research career? How to find a research field that constantly provides me with high impact publications? (Provided I work hard and smart)
P.S: Fluid mechanics is a beautiful field; however, it is so mature that we almost know everything about it.