Chargers, by design, cannot be effective on a team unless the enemy is feeding right into you. Weapons like Jet Squlchers and Splatlings can be more aggressive and push up when they need to. A charger cannot do this to anywhere near the same degree of these other long range weapons. The charger class as a whole is very inflexible when it comes to switching roles on the fly, and in a game like Splatoon where players should be constantly switching roles depending on the state of the game, that means that in most circumstances a Custom Jet Squelcher, Heavy Splatling, Explosher, or any number of other anchor weapons will be better on a team.
TLDR; You should learn charger if you want to be better at snapping to targets. You should not learn it if you want to improve your performance.