From my understanding, statically rendered routes are built entirely on the server and cached. So, this should mean I don't have to worry about network waterfalls when a route is statically rendered and streaming individual components, but I am not sure.

Correct, Static routes at generated at build time and always served from the cache when they are requested either by 1 or 1000 users.
So yes, there's no point on streaming static routes since they're pre-rendered at build time.

That said, here you have to consider multiple scenarios since a route is not always fully static or fully dynamic:
1. If the route is 100% static, meaning it does not contain any async operation going on then the whole route component will get statically generated.
2. If you want the route to be static but it needs to fetch it's own data, then this data will be fetch on build time and will never change since you're gonna be serving the cached results of that first render. I believe this is the default in Next.js 14, but you can enforce this with export const dynamic = "force-static"
3. (This might be the one that interests you) When you want a static route and you also want to stream dynamic segments or components, the only way is to have these dynamic segments wrapped in <Suspense> so the static output generated at build time contains the fallbacks in place of the dynamic slots. And you might want to turn on Partial Prerendering to let Next.js figure out which parts of your route need to be dynamic so it can keep static the rest that doesn't need it.