It's a bit of everything.
I personally have trouble putting an end to my stories, and I have trouble connecting the events that happen. I have sporatic specific events that happen, but what happens in between? I also have trouble choosing what to add and what not to add. In my worlds, I make a life for everyone. Everyone has a past, everyone has things that happen to them, and what do I leave out?
I have no trouble developing enough characters, as I have what, 40 of them? But some of them I have more trouble with then others. A lot of times I go back and enrich their development. I change their character design tons.
I think my writing style would be a bunch of short stories that tie in together in one big story. I don't write too much, though.