It's one thing to sort a list of things by one criteria, say "a". If you have two criteria, say "a" and "b" you can sort by "a" and break ties by "b" or you can sort by a+b or a-b or something like that... But that's not the same as optimizing both things. Maybe you can say "there are these 5 people who are special to me who I never want to miss their posts" but I think people would struggle to maintain rulesets and might not really be happy with the results they get.
In search rankings for instance you night have a document score (like Pagerank) that tries to identify the quality of a document, and you might have a query-document score that identifies the relevance of a document to a query. It's not trivial at all to find a way to blend those that gives you queries that are both relevant and quality as opposed to just one or the other.
The greatest weakness of my current RSS reader is that it's slow, depending on how much I am using it, articles could be delayed anywhere from a day to a week. For certain kinds of articles [1] recency doesn't matter, but other articles [2] have a definite shelf-life and if you repost them too late you look like a total dope.
I'd like to let articles about sports "cut the line" in front of higher quality articles about other topics but it's really hard to find a balance that's right because I don't want to get flooded with lower quality sports articles. It's one thing to say "let people make up their mind about how to balance these things" but when you really try it you find it's pretty hard. Not only do I have to change the whole way my pipeline works (can't be a batch job anymore) but it's not clear to me how to tune up the selection criteria.
If I understand your challenge correctly it could be helped with a reader that gives a taxonomy to classify feeds, as you then get implicitly multiple timelines - one per feed category. Linux desktop readers like akregator and the now abandoned quiterss provide that and it works fine.
If you control the algorithm there is nothing to prevent you from sorting feeds by volume and adjusting their presentation accordingly.
Actually you can imagine countless other UI adaptations depending on preferences, usage patterns etc.
Ideally RSS readers should offer flexible customizations, e.g., with plugins or even some low-code environemnt.