Trigger in automation: Trigger upon completion of previous smart file completion (automations with multiple smart files)

I have multiple smart files in my automations that manage my prospects, & variety of booked clients.     My booked clients  automation is a series of emails with smart files with purposes of providing info & collecting data from my clients.  I’d like to suggest a trigger for the ‘when’ part of the automation flow to be when the previous smart file is completed.  This would allow us to have a fluid and more client friendly experience.  I currently have it timed out based on how many days from the start of the automation or completion of the previous step or number of days before the project date but I would love to have the option to for my clients to move through the planning parts at their pace.   

I attempted to test it to see if it would trigger the next step upon completion of the previous step and if that step included a smart file it would be upon completion of that and tested it with  o days within completing the smart file to trigger the next steps and when I completed the first smart file in the automation it triggered all the steps which had other smart files.   I also tested when previous step was complete and just the sending of the email triggered as a completed step so it sent all the emails at once… so none of the options allow for what I thought it would do.  

 Am I missing how I should be setting this up?  Or Could this be a potential update to the automations to have a trigger upon previous smart file?