Many will have experienced the Return Trip Effect (RTE), whereby the outgoing journey to a destination (any mode of transport) very often 'seems' considerably longer than the return over exactly the same route.

As well as being widely-experienced, the effect is readily reproduced in lab-based experiments - and has been quite extensively investigated.

Despite the investigations, there is still no general agreement on why the effect occurs.

One theory was that it might depend on the familiarity with the route - but this was questioned by a 2011 study :

Three studies confirm the existence of the return trip effect: The return trip often seems shorter than the initial trip, even though the distance traveled and the actual time spent traveling are identical. A pretest shows that people indeed experience a return trip effect regularly, and the effect was found on a bus trip (Study 1), a bicycle trip (Study 2), and when participants watched a video of someone else traveling (Study 3). The return trip effect also existed when another, equidistant route was taken on the return trip, showing that it is not familiarity with the route that causes this effect. Rather, it seems that a violation of expectations causes this effect.

See : The return trip effect: Why the return trip often seems to take less time Psychonomic Bulletin & Review volume 18, pages 827–832

A later, 2020 study found that :

[…] our anticipation account suggests that even when people travel to familiar destinations - such as a son going home from college to visit his parents - they may experience elongated time perception of the outbound trip, even though the destination is one of familiarity and certainty. We believe the present work offers avenues for future research.
[…]
We hope this work also calls further attention to the importance of people’s perceptions of travel time in their social environment. Indeed, a rather large ocean of opportunity appears to exist to better understand the psychological substrates of time perception.

See : Are We There Yet? An Anticipation Account of the Return Trip Effect ^{[ paywalled ]} Social Psychological and Personality Science, Volume 12, Issue 2.

Also see : Time Awarenessplugin-autotooltip__plain plugin-autotooltip_bigTime Awareness

"Anticipating events that will happen in the future is among the most important functions the brain performs. Indeed, it has been increasingly stressed that learning and memory are prospective brain functions; that is, they are only adaptive to the extent that they help animals anticipate and prepare for the future (Dudai and Carruthers, 2005; Schacter and Addis, 2007). To anticipate when events will happen, the brain has evolved mechanisms to tell time across a wide range of te…