This setting is to improve the validation process before the actual Migration is performed.

These results would provide feedback to the user of where in their environments that wont migrate due to paths or names which are too long.

It would be encouraged to perform a validation run before the actual migration.

Maximum destination path length setting

A setting is provided to suit the various SharePoint environments (SharePoint online has a character limit of 400 characters applies to server relative paths.)

Values should range from 1-400 depending on the environment.

Logs

The message the user will see if the validation/migration fails when the character limit has been reached or exceeded.