Should one programmer document another's code?
Several of our lead developers have pursuaded management to assign a junior developer to document their code for them.

Their arguments are:

1.  You'll have two programmers familiar with everything.
2.  It's pair-programming, kinda.
3.  It's more cost-effective = they will get more done.
4.  It demonstrates that their code is readable and maintainable.
5.  They'll be happy to answer any questions; so it's a form of mentoring.

However, the number of programmers they keep busy in order to stay current seems to increase over time.

Is this a good idea?
Should one programmer document another's code?
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Several of our lead developers have pursuaded management to assign a junior developer to document their code for them.

Their arguments are:

1.  You'll have two programmers familiar with everything.
2.  It's pair-programming, kinda.
3.  It's more cost-effective = they will get more done.
4.  It demonstrates that their code is readable and maintainable.
5.  They'll be happy to answer any questions; so it's a form of mentoring.

However, the number of programmers they keep busy in order to stay current seems to increase over time.

Is this a good idea?