The pressure you apply to the hi-hat foot pedal will determine the sound of your hi-hat when you strike it. How your hi-hat sounds should depend on what the music calls for. There are no rules, really.
But, yes, in general its a bad habit and one that I'm guilty of, too. Try adjusting the tension so that the weight of your leg will close it a little tighter(if it's adjustable). That's what I do.



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