alt Hacker NewsSLO timelines are usually over 7d, 30d etc no? and also often don't work that great for backend services in my experience ... they can't give you the level of reactivity that defining alerts about things you care about give you. I'd argue that moving from that direction upwards to figure out what alerts to aggregate and define SLOs around, rather than the other way around in those cases.
Would love to hear more, since I largely used SLOs on backend services (which in turn called other services that also had their own SLOs).
As far as timespans for the error budget consumption, I’ve seen 1 hour -> 1 day -> 1 week. The 1 hour error budget rate would be a page and the others would be low priority.
So you could either keep that as the alerting and/or use the error budget “look ahead” to see if there are more specific alerts you need.