Months into the season, that's not a bad idea. When everyone still has 20 games or so, that's really silly because it's very easy to be victim of unlucky games and that's a huge percentage of your overall winrate.
It's also good to dodge when you feel that someone on the team isn't going to pull their weight w/ their champion. You see the teamcomp is terrible, you op.gg your team. If everyone's pulling 55% or so on their champs, you might as well stick around.
Overall just save the dodges for champions you absolutely cannot deal with playing against, people who are irredeemably toxic/trolling, or getting autofilled into roles you can't play.