Little bit of rambling.

Applejack Arguments!

before I get started, let me be clear.
Applejack is one of my least favorite ponies, but I'm going to be as neutral as possible.

the Question is, "Why does Applejack have so few episodes?"

One Answer:

she works all the time.
Everytime she does have an episode, she's working; Applebuck season, Cider, Last Round up.
Fall weather friends seems to be the only exception to the rule, but we can still argue about how important the Running of the leaves is.
hell, most of her cameos in other episodes has her working: demolishing the barn, battling catterpillers, staring at her trees wondering what happened to all their fruit and leaves, weeding, cooking and so on and so forth.
and when she does have down time, she's reduced to sort of being there.

The one real exception to this rule is Look before you Sleep, really.

as a character, she's backed into a corner, where it's very difficult to write an episode focused on here.

The other Answer:

she's the most level-headed and grounded of all the ponies. sense she's the most normal, it's hard to write for her, sense she doesn't go crazy, act silly, oblivious, etc, etc.

this one feels like a load of crock, sense we've seen her act like an idiot.

I mean, she nearly worked herself to death, yanked a tree into Twilight's window because there was "no time to think", Tucking a tree into a bed, Pretty much everything she's said to Zecora, her initial reaction to Twilight using magic in "Winter wrap up", and probably some other stuff.

And then there's "The Last Round up".
I for one find it difficult to believe that the "Level headed and grounded pony" really though that sending everyone a message that basically said "I'm not coming home.", then continued to dodge the questions surrounding this, and then decided that running away so she didn't have to explain anything was a good idea.

I mean, seriously, does that make sense to anyone?

Here's my honest opinion on the matter.

She has story potential, but those stories will almost always involve the farm and family.
those are her big things, like Rainbow Dash and Flying/The Wonderbolts, Twilight and learning/the Princesses, Rarity and Fashion/status, or Fluttershy and her shyness/animals.

that's not a bad thing, it just makes things a little harder to use.

there will be times that she'll be written poorly, but everyone gets those.

I don't remember who suggested it, but there was a good idea about an Applejack episode.

She finally gets one of those ever elusive days off.
and while she tries to relax, ponies keep coming to her because she's the "Reliable pony who everyone can depend on."
finally, she reaches that point where she's had enough, and tells them that she just wants to enjoy her day off.

"I work day in and day out on th' farm, I spend my free time helpin' whoever needs it, but even I like a little R'n'R every now and then.
can I get that? please?"

anyway, enough about that.