How one uses git is a individual preference ... me, I'll attempt to use it all the time - when moving upwards from within a series ... 2.2 -> 2.3 -> 2.4 -> 2.5 etc. When upgrading not in a series ... the process might be a migration which is not like an upgrade - as folks have been experiencing with the move from 1.9.x to 2.x. Git might still be used with some part of it.
Git from behind a firewall
Git uses a proprietary protocol and it may be blocked by your firewall (port 9418). If this is a problem, you can use Github's http version https://github.com/moodle/moodle.git. It's a bit slower, so use the Git protocol if you can.
Every server/workstation that runs more modern OS has it's own firewall now. Entities in Education/Industry typically do have a network firewall.
Since you remotely host, may/may not apply in your situation.
'spirit of sharing', Ken