What does immense mean in the context of game dev?

On "real" (AA/AAA) games? Easily hundreds of gigabytes or several terabytes of raw assets + project files.

Sometimes even individual art project files can be many gigabytes each. I saw a .psd that was 30gb because of the embedded hi-res reference images.

You can throw pretty much anything in there, in one place and things like locking, partial-checkout, etc. Which gets artists to use it

Perforce also has support for proxies right? It’s not just the TB of data, it’s all of your coworkers in a branch office having to pull all the updates first thing in the morning. If each person has to pull from origin, that’s a lot of bandwidth, and wasted mornings. If the first person in pays and everyone else gets it off the LAN, then you have a better situation.

Yep you can. https://www.perforce.com/downloads/helix-core-proxy-server-p...