I almost always throw the trash in a trash can, simply because that's the habit I got into growing up. There are exceptions though, and I'm not perfect in this regard.
For example, if I have something that's small (like gum wrapper or gum itself), and there's no trash cans nearby, I try to throw it into an inconspicious place, so that hopefully no one really notices it.
If there's a ton of trash around already, I'm less inclined to throw it in the trash can if there's none nearby (I'll walk towards one if it's near, but if I have to go really far for it, I'm just ditching it).
If I shoot garbage into the bin, and miss, if I think I can get away with it, I'll just leave it. However, if there's other people present, or the trash is in a public area (like a hallway), I will usually pick it up and throw it in (or "bomb it at close range" lol

)
Jam it back in, in the dark.