Please disregard the bottom portion "Field Description" this is not apart of my questions

I've been looking at the different documentation on how average time on site is calculated however I'm confused by how the Average Time on site Totals is calculated (in screenshot 00:09:16)  From my understanding If I'm looking at a page name for my dimension, the average time should be calculated b...

I've created a free form table, my dimension is marketing channel  and my metric is visits the number comes up as 111,567 . However, if I were to add in unique visitors to the same table with the same date range, my visits changes to 156,283. Is there a reasoning for this change? I saw that @Jennife...