u have read my other topic so i'll complete it here
I need the three requisites to use because of the lack of a good linked technology system between the ages!
so i could link Knights with Horseback Riding, The Wheel, Iron Working, Monarchy and Monotheism, all these should be needed for example to get a knight!
Using three requisites or four for the unit, would make me get past the problem with the technology tree.
Plus i don't believe there should a barrier, if u have the knowledge u should be able to go all the way in one thing, and lacking the other... but with my idea most of the advances are related... so noone starts from 0 on every new age, and no-one would need to complete all the needed technologies to get the next one. For a scientist, expansionist civilization, would probably have literature and construction, and it should be able to go the next step, to engineering. which is how i linked it