It honestly depends. I'm a historian and teacher - my undergraduate and postgraduate focused on Ancient Rome and I have been to Rome numerous times as well as a visit to an archaeological excavation in Carriage (modern Tunisia). It has given me a better understanding and context for my research. To walk through the Forum, I wonder if I were to close my eyes would I just once open them onto ancient Rome itself....
I have also done extensive research on Tudor England for coursework at Cambridge - the majority of my time is spent at the National Archives in Kew and the British Library. I do plan to visit the Tower of London next week to once again get a better understanding and awareness of key moments in Mary I's reign (and the whole Jane Grey issue). I will walk through places where she stayed, lived and ultimately, was the focus of early modern kingship.
For me, it is invaluable. I am thinking of doing further research on Whitechapel in the 1880s and plan a walk there before winter, which could be interesting...