Do I need to choose a mirror for a server or a not moving computer to reduce the load on the central servers?

deb.debian.org is somehow load-balanced using a global CDN. Will this CDN-backed service pick the fasted mirror for me every time I update or will it just load-balance within the infrastructure of Debians main servers? The connection and download speed is not very different when choosing a mirror near me or just using the default.

I want to do what is best for the project.