Every extravert function requires people to be fully develop and every introvert function requires private time to be fully develop. It is possible to develop any extravert function and keep it private and to develop any introvert function with people around, though. This is a transition stage and has many of the advantages of fully developing the secondary without the high energy costs.
Te:Making sure you can reach goals, setting goals that only you know. Examples:Like making a puzzle or fixing something that no one expects you to fix
Fe:Making sure you could interact with anyone you decided to. Examples:Fantasizing about winning arguments and interacting with others. Rant anonymously through the web
Se:Making sure you would made an impact if you decided to. Examples:Spending a lot of time trying outfits or accomplishing a highscore but keeping them private
Ne:Making sure you have fresh and out of the box ideas by comparing them anonymously with other's people.
Fi:Making sure you are 'good' by leveling yourself with other people around you.
Ti:Being true to the mathematical complexity of the world, only when you have other people to bounce ideas with.
Si:Being true to your own mental model, only when you can check it with others.
Ni:Making sure that not everything is what it seems, when you can check your assumptions with others.
---
Roughly, the transition stage happens to introverts when they know that they have an stake in the real world but they are always focus on their State of Grace. The transition stage happens to extraverts when they know that they want to reach a State of Grace but they always focus on their real world stakes.