Delay in flight progress display

I read the FAQ section and understand that there might be a “slight” delay in displaying flight information and it supposedly could reach 5 minutes.
However, I see delays of close to 15 minutes. An airplane is cleared to land and then taxies to parking but FA shows it at 15,000’ still 15 minutes (60sm) out.
This seems like a little more than just a “slight” delay in data display. Any idea what’s causing it and are you guys even aware of it?