Downloads are kept and reused. Setting up a second game fetched the same 165 MB model, the same OptiScaler zip and the same ReShade installer all over again. They are now kept in %LOCALAPPDATA%\dlss5oneclick\downloads and copied from there, so every game after the first installs at disk speed and costs nothing in bandwidth (#42).
A release asset URL names its tag, so the bytes behind it never change and the cache can be trusted. A URL that does move under the same address — anything under /releases/latest/download/ — is never cached, so you still get the newest build of those. The folder is capped at 2 GB and the oldest entries go first; deleting it is safe at any time.