What do you think starlight has been doing in the episodes that we don't see her?

My theory is that she’s off visiting sunburst, keeping an eye on the castle, doing friendship lessons or visiting the equal village.

Hanging with Trixie, doing charity work for orphanages, disctributing pamphlets for Rarity.

I think she’s a boring character. And the fact that she’s gonna be one of the Mane 7 makes me worried about the destiny of the show.

@09MurphyM  
Hanging around thd castle doing whatever, presumably.
 
@Ring Team  
She isn’t any Mane anything.

Doing poni things.

Plannong for the Season finale. I don’t know if it will involve gratitude or betrayal, but she will definitely have something to do with some sort of season-long story arc.

Rolling in flour so her body looks white, then giving Spike the closest thing to the good time he wants, that he’ll ever get.

Training just like in S5 so she can come out of nowhere during the finale and throw a Spirit Bomb at the villain.
 
She used the Power of Vengeance for her first boost, so now she’ll go just like Frieza and show what happens when she actually gives a shit about being a super-unicorn and trains for it. Poof, suddenly she’s an alicorn ten times more powerful than Twilight.

@Poison Trail  
God no….

What some of these guys have already said what with hanging out with Trixie, Sunburst, the Our Town townponies.  
But one thing that I should bring up is on how life is for her during the phases of her role in the show. Before establishing Our Town her situation was left ambiguous. Did she leave immediately after Sunburst left her or when she was older? She’d likely have needed to travel far in order for anyone in her hometown to not recognize her and make things awkward.  
As for maintaining her town, she’d still need to work hard to keep things in order, but Double Diamond and some other ponies seemed to be loyal followers to help her out.  
As for after losing her town, she’d definitely would have needed to work her plot off as she’d first need to navigate out of that cave system she escaped into, find a job, shelter and etc that was flexible enough to allow her to spy on Twilight, avoid getting caught by both Twilight and her friends and the authorities (assuming Twilight wasn’t stupid enough to report that a cult leader is still on the loose) and finally figure out how to improve Starswirl the Bearded’s Time Travelling spell.  
And then you have S6 Glimmer who has life easy by living in a comfy ass castle with the excuse for being a pupil to a princess, with only a few minor hiccups there and there. (I mean she still probably works with Trixie and they both share the profits, but still what exactly did she do before No Second Prances?)