From my experience flat RR doesn’t really scale well.
But about drawing the line: as a builder, personally, I think it should be all about efficient and sustainable farm models. Because otherwise having access to GDstash we can just put out 4 level 3 banners, take 4 blessings and drink all the potions and whatever. And next logical step would be tweaking core stats and giving your char few extra skill points, because why not.
That’s why I don’t like speedrunning meta, because apparently anything goes, even deducting seconds that take you running to Lokarr after 160 ends and using a build that would die like every second or a third time. Then why not use 4 level 3 banners of all types then?
But ranting aside, if your setup has the same efficiency time wise as 4+3 or 3+1 then why not. But then if that model takes much more time to replenish tributes than just one 1-10 run then it’s not efficient really. So gotta do the math on that.