Having inspiration cast on city, as well as more essences (not mentioning conclave + upgrades and specific improvements) will always affect your research rate, as well as city level / growth and unrest.
AI's will always trade techs and make pacts with each other as well.
Regarding that, it depends on their traits and goals. I always have Magnar starting the towers before anyone else if he's present in game and in top 3 faction power.
Personally depending on faction I play I might not bother with magic research apart from shard harvesting until well into the mid game, other times I would focus on it at expense of warfare and some civilization 