Does the length of time a collection can report get extended when the collector updates the account, or when a new collector buys the debt?

Reporting Period Limits are Fixed

No. When a new collector takes over a collection account they are supposed to inherit the original reporting period start date. Collections are supposed to stop reporting seven years plus 180 days from the original date of default.

Learn to Count the Dates

The reporting period start date for a collection has nothing to do with the open date that you see on your credit report. If you want to figure out when the collection will stop reporting count the seven years plus 180 days as indicated above.

Always Check the Facts

On the other hand, collectors are notorious for accidentally resetting the reporting period start date. A percentage of these resets may be intentional, others may be caused by human error that might arise as the accounts are sold and re-sold. Either way, if you see a collection that is reporting beyond its limit, it’s time to send a credit repair dispute letter.