Please help: Repeat medical question.. Consular process

[rndman]

I was told that if the applicant fails the medical and for it pass had to undergo treatment, the repeat medical can only be done after 1 year (even though the item under question gets resolved by proper treatment in less than a year) .
Is this true?
If it is, then consulate provides only 1 year to submit the documentation on 221g. How does that get extended?