I always post the cap. I guess I am a little compulsive with it comes to using a fountain pen, I also make sure that the clip is aligned with the nib tip. To me, that is a big part of the pleasure of using a fountain pen.
+1
I'm like that with the lid of my teapot too! The hole on the lid has to be at the back in line with the handle! I'm not OCD but it makes my daughter giggle.
Oh yes..... Cap on......For me anyhow.