I have struggled with this as well. In fact I got here with a google search of exactly the same question. Reading all these answers finally painted a picture in my head and I decided to try to get this down looking at the state of the 2 repositories and 1 sandbox and actions performed over time while watching the version of them. So here is what I came up with. Please correct me if I messed up anywhere.
The three repos with a fetch:
--------------------- ----------------------- -----------------------
- Remote Repo - - Remote Repo - - Remote Repo -
- - - gets pushed - - -
- @ R01 - - @ R02 - - @ R02 -
--------------------- ----------------------- -----------------------
--------------------- ----------------------- -----------------------
- Local Repo - - Local Repo - - Local Repo -
- pull - - - - fetch -
- @ R01 - - @ R01 - - @ R02 -
--------------------- ----------------------- -----------------------
--------------------- ----------------------- -----------------------
- Local Sandbox - - Local Sandbox - - Local Sandbox -
- Checkout - - new work done - - -
- @ R01 - - @ R01+ - - @R01+ -
--------------------- ----------------------- -----------------------
The three repos with a pull
--------------------- ----------------------- -----------------------
- Remote Repo - - Remote Repo - - Remote Repo -
- - - gets pushed - - -
- @ R01 - - @ R02 - - @ R02 -
--------------------- ----------------------- -----------------------
--------------------- ----------------------- -----------------------
- Local Repo - - Local Repo - - Local Repo -
- pull - - - - pull -
- @ R01 - - @ R01 - - @ R02 -
--------------------- ----------------------- -----------------------
--------------------- ----------------------- -----------------------
- Local Sandbox - - Local Sandbox - - Local Sandbox -
- Checkout - - new work done - - merged with R02 -
- @ R01 - - @ R01+ - - @R02+ -
--------------------- ----------------------- -----------------------
This helped me understand why a fetch is pretty important.
