how does visa journey come up with the timelines

[Beauty for Ashes 257]

How does visa journey come up with timelines? I have a friend who filed at the same service center 2 months before me with a receipt date a month and a half apart for a 130 and she got her NOA2 August 20th. I am trying to figure out how visa journey comes up with the date. Do they use the other people that have been through that consulate or is it a system wide date calculator? I am confused. November 29th seems very far out of the I130 approval considering my friend got hers in about 120 days. How do they come up with the times?

[Jasman0717 9]

The timelines are based on people filling out their timelines as they progress through the process.

[Beauty for Ashes 257]

The timelines are based on people filling out their timelines as they progress through the process.

so people with slow processes can either speed up or slow down others