You cant quantify enjoyment of a journey with time. Still, I think you need to include it as a parameter, for the journey organization, because of the increased focus on the reason why you travel – what ever it is.
10 months? 3 years? For ever? I don’t know. It highly depends on your economic income/outcome; reason of journey; future interests; travel partner; and any unpredictable events. I do love the idea of traveling for an unpredictable time; to know that it doesn’t matter if you accidently stayed for a very long time in that comfy hut: with the beach just outside and only your own reflections to worry about. But how good shape would the chocolate cake be in if it didn’t have the baking tray as a framework on how far it could go. You could pour more chocolate in… but if the tray is too wide – it will get flat.
Gastronomic vagabond 