[Avodah] why stop learning?

[David Riceman]

Me:
>> Where is the evidence that learning or doing chessed "for the zchus" 
>> of a person has any effect? What mechanism induces that effect?
RZS:
>
> 1. The story of Rabbi Akiva having a rasha's son say kaddish for his
> zechus.
>
> 2. Yissachar/Zevulun
>
> 3. The gemara in Rosh Hashana 4a about giving tzedaka "so that my son
> should live"
>
This is why I regret having missed the beginning of the discussion.  In 
all three of these cases the zchus is causally related to the reward:

1.  The son would not have been able to say kaddish without his father 
having sired him.

2.  Yissachar would not have had so much time to study had Zevulun not 
supported him.

3.  The father would not have given tzedakah had his son not been ill.

But when I was in yeshiva sometimes someone would ask us to dedicate 
today's learning for someone we'd never heard of, when we would have 
done the same learning regardless.  How does that work?

David Riceman