If you follow god and his friends

There was a reason for their sojourning

They spent some time sightseeing

You try walking in the desert with a whole city of slaves who now are free and just want to party. Trust me it will take you 40 yrs.

"40" is Old Testament for "really long time" (40 days and 40 nights as the second example). It could be 6 days walk, which in a desert I imagine us still very long.