A lot of this stuff seems obvious and self-evident, and I wouldn't be surprised if much of it was supported by actual research, but you're absolutely right that

A lot of this stuff seems obvious and self-evident, and I wouldn't be surprised if much of it was supported by actual research, but you're absolutely right that self-reported data gathered from internet surveys is questionable at best. Every person has their own definition of what their "productivity" even means, they each have only their own subjective measures of their own productivity, and there's no verification to check who is providing the data, to catch those who simply outright lie or to catch people who click through the survey without even reading/understanding what is asked. Two people could both report 10% higher productivity when in fact there is nothing similar about their productivity levels at all. Internet polls and surveys are cheap and easy which is why so many people use them, and they can be pretty fun when all you're trying to find out is which celebrities are popular or which harry potter character you are, but they are generally terrible for getting data useful for actual science or for anything where accuracy matters. It's no wonder that there's such a huge reproducibility problem in social sciences considering the heavy reliance on self-reported data through internet surveys.