Trade routes to City States

Is there any benefit in establishing trade routes to CS once your cities are at a good level or should this only be done if a particular CS requests one? I've never really done it myself but I notice that when a CS asks for one, my workers start building roads to the city in question. Should I start building roads to CSs once my workers are finished improving my cities or would this cost more than it's worth?

First you shouldn't automate workers, never ever. Apart from the fact that you may want to prioritize different things, they use really silly rules for improving (for example if you are in a Golden Age they will build Trading Posts all over because they yield an extra gold), they don't change improvements, and if they also build roads without you ever wanting them they cost a lot of GPT.

A road to a CS for the Quest is worth it but you can micro it to save some of GPT: pre-build the road, and stop when there is one turn left. Build the first road tiles in the CS border, and then finish the final segments quickly since they require a single turn, thus minimizing the maintenance cost to a small amount of turns. Once the road is complete and the quest is completed you can delete the road tiles and save on GPT.

Sending trade route to city states is less optimal, but in some situations it is worth it: for a cs quest, if you need to send a safe external route and you expect war with neighbors, on lower difficulties when you don't want to give beakers to the opponent, and of course if you are Germany for the production bonus.

Wait... you ask about roads or trade routes?
Those are 2 different things. Trade routes are useful... they give you nice amount of money. Ofc it is not as useful as sending the caravan to another civ (if you have caravansary) which will boost the income for you and you will get science/religion too

Building roads toward CS? uhm I wouldnt do it unless i plan to completely integrate them with my empire diplomatically and even then i`ll do it at later stage when i have enough money to spend and i am sure i wont loose them as ally

Sorry guys, I don't know what I was thinking when I typed 'Trade routes' lol! I meant to ask about roads to City States!!!

If I would otherwise have an idle worker, I will often have them build roads in CS territory. The road quest are unpredictable, but seem to more likely with closer CS. Waiting means having to deal with more and more CS units that are in the way. Roads you build in CS (and in AI) territory do not cost you maintenance. No, you should not start building roads to CSs once your workers are finished improving your cities. It will cost more (1gpt per road tile) than it's worth (which is nothing, until (and unless) the quest comes online). You should start building roads from CS territory (and only on CS territory) if you have workers with nothing else to do.

Trade routes to city states were not always necessary. Trade routes to city states should only be built when theres a city state quest demanding it.

Here are a couple more tips for CS road quests:

• They can go through AI territory (so long as you have open borders) and other CS territory (but only count for the quest if you have friend or ally status).
• You can build roads completely ahead of the quest without jeopardizing that it might be offered. (Which seems like a bit of an exploit, but I take advantage of it.)

And if you want to go for the cheese you can disconnect it right after you've gotten the influence to save on tile maintenance.

That is not cheesing it, why would you keep the road? It's just costing you money.