Definitely, unless the original source was very inefficiently compressed, it's not worth the time, effort and quality loss to save a small amount of space.
Thanks for asking this, one of the devs in the AMA was talking about Bittorrent for sharing the serving of instance-hosted files in a way that made me think "sounds like you want IPFS". Now I'm not so sure.
I'd never heard of grassy tramlines, I love them! I've never seen any anywhere, and I've been all over Europe, they are either quite rare, or I haven't been paying attention.
Definitely, unless the original source was very inefficiently compressed, it's not worth the time, effort and quality loss to save a small amount of space.