Goal criteria helps gauge success: Use goals in contact-based workflows
And for Contact workflows you can use that to unenroll contacts from a workflow when they meet a set goal.
I think a big piece of keeping documentation up to date is being able to lock down permissions for editing workflows…seems like a lot of users have Super Admin access and mess with things they shouldn’t. 
I would love to start seeing HubSpot Super Admin seen on the level of Salesforce Admin - where a process needs to be followed to request a change from the designated person, who would then know to document their changes.