blazar,
When I have requested help, I try to respond to each unique reply with feedback along the lines of:

• Thanks, this is exactly what I was looking for
• Your solution doesn't work because X
• Your solution works but I chose to go with Y because Z
• You answered the question I asked but I really meant X
• etc, etc, etc

I do this so that others reading my thread in the future, with a similar problem can immediately see what did and did not work, what considerations I made to render my decision, etc. It also gives feedback to the person providing the response that they are appreciated and potentially point out flaws so they themselves can learn.

I resevere just /msg response when I am not adding anything to the content of the thread. This might be to some responses that said the same thing as another in the thread I did reply to.

This is all very much subjective.