As I've mentioned in other threads, I'm a big believer in befriending city-states for the bonuses they provide. Many claim that they aren't worth the investment because at higher levels the AI just wipes them out, but if you can have your cities envelope a city-state it won't be conquered, and if you can border a city-state you can always liberate it. Not just the Suzerein bonuses, many of which are really good, but also simply the 3/6 envoy level bonuses can have a profound impact on your civilization-wide yields.
That being said, I usually have one card slot permanently reserved for charismatic leader (and later gunboat diplomacy) to try to get the maximum number of envoys in a game. However, after reflecting over my last couple of games, I don't recall the "envoy clock" hitting full circle that many times in a game, even when permanently securing the bonus from charismatic leader (and gunboat,) I think the majority of the envoys that I got were from city-state quests, I prioritized them, especially with CS's that had bonuses that I really wanted, and I was usually able to get an extra envoy with at least a third of the CS's, usually more like half of them, every era. There are also numerous civics that give bonus envoys which accounted for the second-highest source of envoys I received (side note: I also found it very effective to skip some of these civics, which later in the game gave me the option of completing them in a single turn for an instant envoy to re-suzerein a city-state.) Those two sources of envoys, quests and civics, seemed to account for the vast majority of envoys that I received, and the envoy-clock would still be ticking if I wasn't running charismatic leader, just a little slower.
So back to the question: is the charismatic leader card worth it? Many other posters here seem to hold it in high regard, and since I value envoys highly it seems to have a high value in theory, but in actual practice I have considerable doubts about it's impact.
That being said, I usually have one card slot permanently reserved for charismatic leader (and later gunboat diplomacy) to try to get the maximum number of envoys in a game. However, after reflecting over my last couple of games, I don't recall the "envoy clock" hitting full circle that many times in a game, even when permanently securing the bonus from charismatic leader (and gunboat,) I think the majority of the envoys that I got were from city-state quests, I prioritized them, especially with CS's that had bonuses that I really wanted, and I was usually able to get an extra envoy with at least a third of the CS's, usually more like half of them, every era. There are also numerous civics that give bonus envoys which accounted for the second-highest source of envoys I received (side note: I also found it very effective to skip some of these civics, which later in the game gave me the option of completing them in a single turn for an instant envoy to re-suzerein a city-state.) Those two sources of envoys, quests and civics, seemed to account for the vast majority of envoys that I received, and the envoy-clock would still be ticking if I wasn't running charismatic leader, just a little slower.
So back to the question: is the charismatic leader card worth it? Many other posters here seem to hold it in high regard, and since I value envoys highly it seems to have a high value in theory, but in actual practice I have considerable doubts about it's impact.