I can see some merit in this, a story will often reveal the problem better than cold analytics, but I have to say I still think the common approach of defining the objects and then the actors is going to get a better outcome.
My rule of thumb for the last 25 years has been:
Double how long you think it will take you to do your bit, then go to the next set of units.
e.g.
5 minutes becomes 10 hours
1 day becomes 2 weeks
2 weeks becomes 4 months
When you write code it's easy to forget the testing, documentation, and process and people overheads of getting your code out of your head and into production.