"Last Touch" doesn't retroactively overwrite previous values....
So let's look at the example above in more detail:
- Newsletter
- Page A
- Marketing Channel: Newsletter
- Page B
- Last Touch Marketing Channel is Newsletter
- Social Media Site
- Page C
- Marketing Channel: Organic Social
- Page D
- Last Touch Marketing Channel is Organic Social
- Page E
- Last Touch Marketing Channel is Organic Social
- Google
- Page F
- Marketing Channel: Search
- Page G
- Last Touch Marketing Channel is Search
Pages A and B in the Visit are Last Touch Newsletter
Pages C, D and E are Last Touch Organic Social
Pages F and G are Last Touch Search
So you will still see all three Marketing Channels within your visit, the "Last Touch" will impact at a page level
Now, if you are looking at "First Touch" within a visit, then the first reported Marketing Channel for the Visit will show Newsletter