Not at all. Learning to manage your civ in a reasonable timeframe is a skill. Yes, you can't check every city every turn and go through a thorough, statistical analysis of every facet of your civ. I doubt most people do that in single player, either. Prioritizing what's important, and leaving what has only a minor impact out is crucial.
Honestly, I can't say that there's much I would do in single player that I don't have time for in multiplayer. I often find myself sitting around, generally doing something esle, while I wait for the turn timer to tick down in the later part of games. Yes, it's quick when you first play, but you get used to it quite quickly

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Well thats what difficulties are for. The AI is not a match for a decent player on even odds. Thats why you play higher difficulties to give them bonuses.
Im not skilled enough to play above prince right now.
Really, it's not about skill. Yes, it's important to understand the the game and to grasp the basics of strategy. After roughly monarch level, though, most of the "improvement" that players do as they progress up the levels is that they learn new ways to abuse the AI. They learn to go into favorite civics (although, to be fair, this was an intended prat of the gaem), they learn to plant a wall of undefended or underdefended cities to block off AI expansion (something which would never work on a human), they learn the predictable AI tech path, and promptly research ignored techs so that they can go around trading it to every AI for a different tech. Take it from me, not much more "skill" at actually playing the game is required to beat deity than monarch. All that you need is a more intimate knowledge of how the AI plays.
In contrast, multiplayer is filled with strategic aspects. Yes, some players can be predictable, but humans rarely if ever fall for the same strategies that the AI does. Nobody will trade you Civil Service for Compass. Nobody will let you take their land with empty cities. The best multiplayer games are won by using new approaches on unsuspecting opponents, but, except at the very highest levels of play, raw skill alone is often enough to win games. The best player wins, not the one who is willing to reload combat or run a complicated statistical analysis for hours on end. It's much more fun, in my opinion

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