I think that regular stuff dropped on the ground should stay a day or two but summoned arrows should disappear instantly. Had a big dragon fight at the college a few days ago(game time) and there are still tons of summoned arrows sticking straight up in the ground

Bug or a feature?

Yeah, I still see Bound Bow arrows sticking out of the ground from places I really have to struggle to remember when I was last there.
I guess the time limit on a Bound Bow doesn't affect it's arrows. lol

Its a bug most things in the game doesn't clean up.

Its an annoying bug, items never clean up, neither do ash piles and enemies do not respawn outside of ruins.

Sadly the one thing I want to stay around, drain skeletons, disappear rather quickly. I enjoyed having them pile up in Riverwood.

It's a game feature, you are a much better Conjurer then you give yourself credit for.

It's a bug.

To fix it, just open the command console, click the arrows (make sure you have the arrow selected and not the ground) and type disable. Then type MarkForDelete.

I wish I had a PC to remove ash piles, weapons, and I want enemies to respawn!

I haven't tested it but maybe if you pick up dropped weapons and store them in a container so they get autodeleted? Might help prevent savegame bloat.

Enemies should respawn in dungeons after 30 in-game days. Outdoor enemies take less than that, like 20 days or something.

That is what I have been doing with the weapons. The arrows stay around too, they are difficullt to find.

I know how long it takes them to respawn its been over a year in game time and several areas outside of dungeons have not respawned. It might be affected by the weapons not disappearing, I have a theory that the enemies weapons might be to blame, I have went back to the areas and the weapons stay there and the enemies have never respwaned, I waited about three months for the game to clear itself of the junk around and respawn the enemies.

There is some junk i dropped in the area with the summoned arrows. I clean it up and see what happens

Regular arrows are capped at 100 in the game world at any given time. They'll stay there forever, but as soon as someone fires that 101st arrow, arrow number 1 gets deleted.

It would appear that Conjured Arrows are not affected by this.

Stupid arrows.

You can make them vanish with SkyEdit (I'm assuming), much like the arrows shot by the Dwarven Spheres also disappear, by checking the box labeled "Vanishes" while editing them. That's only if you're on the PC though.