When does server-side rendering (SSR) actually improve perceived performance for web apps?

Hey everyone, I've been thinking a lot about SSR lately, especially with modern SPAs. On paper, it sounds like such a good idea for how fast pages load at first and for SEO. But sometimes, when I'm actually working with it, the server has to do so much work to render things, or it's just really complicated to get a big app hydrated. That can actually make things feel slower or cause more flickering. So, when do you guys think SSR is actually worth all that extra work and potential speed bumps? I mean, especially for apps that use a ton of data or are super interactive. Are there certain kinds of apps where it's almost always the best way to go, and others where you just shouldn't even bother?