Shark Diver
King
When not going for CV, do folks open Aesthetics and then take the SP to get the half price cultural buildings? For me, this delays finishing out Rationalism by at least one SP, but it seems well worth the detour. As joncnunn wrote, Hermitage is a great NW, even with the steep prerequisites.
To me, it is not worth going this route. Because the culture buildings that benefit from this policy are relatively late, they get built pretty quickly without using a valuable SP to shave a few turns.
Are you delaying finishing Rationalism before ideologies or after ideologies? If before (that's a rare luxury), then the cost/benefit is a few turns of production vs. +50% from RA's AND whatever random opener benefit you might choose. I don't think it's close. If it is after ideologies, then those buildings should have long since been built to get much benefit. Is the 25% GWAM bonus (+ maybe Uffizi) AND cheaper cultural buildings worth more? I guess it could be situationally, but you did say "when not going for CV".