I'm a little confused about the idea of filling in specialist slots in each city. What i do currently is let a city to get to level 10+ pop and i will fill in specialists slots as long as my food stays positive and city is able to grow. This means that eventually when my city hits 30 or so pop, i have all my slots filled in for that city while still growing. My question is should i be specializing each city only for certain type of specialists, like 1 science specialist city, 1 merchants, 1 guilds? I try to build all the culture guilds in 1 city but i'm not even sure if that makes any difference or they can be spread out. Second part of this question, should i be building guilds at all, even if i'm not going for a culture victory?