For me, it's because I hop between development machines, and pushing/pulling a branch is much easier than the alternative of synchronizing files manually among said machines.

Also, so that if something goes awry with my dev machine for whatever reason, at least my work is saved.

Also, to make it easier for a colleague to review my code before it gets merged into something.

Also, becuase it means I can use GitHub's PR system instead of doing it on my machine (thus providing some additional record that my code got merged in, and providing an avenue for the merge itself to be reviewed and commented on).

We have a rule that you never go home at night without pushing your work, even if it's garbage. Put it in a super-short-term feature branch if needed, and push that, but don't leave it imprisoned on your machine.

There are people who follow this rule, and there are people that think disk failures are what happen to other people.

Few things sting as bad as loosing hours or days worth of work.

And there are people who have good backup systems.

It allows builds off of that branch, so you can get test feedback etc. It also acts as sort of a backup or a sync if you switch machines.

Code reviews -- you can create a PR on the pushed code, make fixes in response to the comments, rebase, and re-push.

I work on multiple machines. Pushing my branch up even if it's busted code means I can continue work easily on other computers.

Immediate backup

(I hope I'm not alone in saying this...)

I kinda hope you are, because backup and source control really should be separate functions. Obviously your source control repository should be backed up, and pushing stuff into it acts to create a backup, but you really should have a separate backup system at work as well, to cover unpushed code as well as all the other useful info contained on your computer.

I use it the same way too. I do not really see why backup should be separate from source control as there is no valuable information on my (work) computer apart from the source code, and I never spend more than a few hours without pushing.

Backups of your work computer would close that hours-long window between pushes.

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