Hi again. The note volume stays to whatever it is sled to after. The effect itself slides the volume of the note played and not the sample itself. Keep in mind that "Volume slide" is not only an effect command but also a volume command. What do I mean? In XM and other later tracker formats you can do like so:
c-5 18 v64 ---
--- -- c01 ---
--- -- c01 ---
--- -- c01 ---
--- -- c01 ---
"c01" here is a volume command, which tells the note to slide volume. In this case, slide upwards. to slide it down, you use dXX command. This is useful for many different cases, like for example if you want to keep portamento while you're sliding volume.
Also keep in mind that there is an effect like "Kxx" which is a VolSide+Vibrato and "Lxx" which is VolSlide+NotePorta
It's ultimately up to a composer on how to use the tools.
Also, you can keep it in one thread. It's okay
Hope this helps