Why use fork in GIT?

Hello guys,

We use GIT alot, but I might think we might not use it in the best practice way, since we do not use fork.

We use it like this:
1) clone our repo and set up the dev-environment, this is just done once.
2) When we start on a new issue we do git pull from master
3) create a branch for the issue
4) do the developing
4a) if the developing take a long time we might do a git pull in master and merge it to the developing branch, just to keep up with other developers work.
5) When done developing, we do a git pull in master and merge it to the developing branch (take care of merge-problems in developing branch)
6) Create a pull request from developing branch to the master
7) Merge from our build-server

I new team member told us that it is better to use fork but he could not explain why it would be better.
How ever it looks like the process with fork is:

When we start on a new issue we do
1) fork the repo (with autosync on), and set up dev-environment, this is done every time.
3) create a branch for the issue
4) do the developing
4a) if the developing take a long time we might do a merge from master (it should be autosynched) to the developing branch, just to keep up with other developers work.
5) When done developing, we merge master to the developing branch
6) Create a pull request from developing branch to the master
7) Merge from our build-server

If the later is the best practice I frankly do not see any advantages.
The later also seems to be more time consuming if the set up of the dev-environment is complex.
Do you guys see any missunderstandings?

Best regards
Fredrik