I haven't dug into too much detail, but doing git gc did have a noticeable effect on size and subsequent update performance. I assume, some temporary artifacts got consolidated.

Also resetting the repository once every 1-2 years, and keeping the old one for a while is fine for smaller setups.

Depending on your business size and the amount of resources you want to allocate towards "basic system administration", accomplishing the same task with fewer tools could have its advantages.