If you always end up with rubbery, overcooked, scrambled eggs, you are probably using too much heat.
Protein and high heat don't usually mix well.
Regardless of the ingredients you add to your eggs, be sure you are using the proper heat. Temperature is the number one thing to blame for those rubbery, scrambled eggs.
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[THE ONE THING YOU SHOULD NEVER DO WHEN MAKING SCRAMBLED EGGS]