Just out of curiosity do Notes, Letters and Writs stay where they are if you read them only and dont pick them up?

I talking abouts notes such as Bolars Writ, Gauldurs Notes...etc

I'm interested in just leaving them where I found them and only reading them and taking the weapon/reward. Does the note disappear after awhile, do they respawn if you take them?

I think some stay if you don't pick them up. Others can respawn after a while. The Thug's Missive comes to mind with the Dragon Priest Shrine. I think that one respawns.