Ask HN: How do you decide whether to use a SPA or not?

Assuming you can make the choice, how do you decide if you want a single-page application or a good ol' server rendered sprinkled with JavaScript one?

I've had an idea for a project I want to build for a while. It's pretty CRUD-y but the resource the users have is a "timer", so to speak. Basically, a runnable recipe that counts down with time and shows which ingredients to put in at which time.

Everything can be server-rendered except the actual timer, which is what makes the choice hard for me (I'm fairly inexperienced and only been forced to do SPAs at work).

Assuming I go server-renderd, what should I use for the JS such that the timers are just "components" that are easy to render but don't take over the page like a full SPA would?

Thanks.