The Detour tool is really useful in Alteryx when you have something you would like to have under one condition and something else to happen with other conditions.
Lets take a quick look at Alteryx's example and description for the Detour and Detour end tools.
I recently used multiple detour tools to help me solve an Alteryx challenge.
Here I have two check boxes that have conditions I would like a user to be able to set.
The first checkbox is for whether the user would like to see Legendary pokemon in their output. By default the answer is no so the data goes through the left portion of the detour and legendary Pokemon are filtered out. However if the user does click the checkbox there is no need to filter the data and the data just goes straight through to the detour end.
The 2nd detour tool is similar but with the situation reversed. By default all of the data is allowed through and only if the box is checked does the data go through the right and get filtered.