How long to repair credit score
Once an account is charged off then nothing can re-age the reporting period. Any payment(s) made after an account is charged off would not re-age the reporting period (it is illegal to re-age the reporting time period). Though it might reset collecting SOL, that is if your state allows the collecting SOL to be reset.
You were pretty vague about what type of "single event default" you're talking about.
If it was a single late payment. the late payment would be removed 7 years from the date of the late.
If you had a credit card, mortgage loan or a non federally backed student loan that you just stopped paying on and then it was charged off. it would be removed 7 years + * 180 days from the date of the first missed payment and the account was never brought current leading to the charge off. (any payment after the first missed payment that does not bring the account current, before the account is charged off, would not count
as the default date)
If it was a federally backed student loan and you stopped paying on it then it can continue to report until 7 years after it's paid.
* The extra 180 days was added to give original creditors a little flexibility (in case they had shoddy record keeping and couldn't provide an exact date of the first late). Often, though not always, once a charge off had reported for the first 7 years, but still has the extra 180 days to go, then an obsolete dispute may work to get it removed.
A late pay or a default on a mortgage or student loan (especially mortgages) carries more weight with FICO and with lenders then lates or defaults on other types of accounts like credit cards, general loans, etc. Because of that it could take a couple of years longer for it to stop having a large impact on your scores or how lenders view your reports then it would if it were a credit card, etc.Source: www.city-data.com