The answer he gave if it was indeed him is incorrect. Additional information is not ALWAYS part of the process. A 510K can be approved without additional information if submitted correctly.
There are two types of additional information that can be requested
a. Interactive review, where the reviewer asks questions or requires additional information and thinks that these can be answered without putting the application on hold
b. Additional Information, where the reviewer asks for information and expect an answer. But in this case, he puts the application on hold until the questions are answered, without resetting the clock.
Essentially, it is within the FDA target to complete the application within 90 days, however, the days are counted except for when the application is on hold waiting for an answer. In principle, an application can take a year to be approved, but in the FDA books, it took no more than 90 days, based on how the FDA defines the days.
In summary, there seems to be a misleading information with the average time for when a 510K is submitted and for when a 510K is approved. That average time is pretty much meaningless.