Hi there,

In the tutorial you're referring to here: https://www.guitartricks.com/lesson.php?input=22946

Lisa teaches the E minor chord and when she explains "how to strum" the chord, she does say to hit the Low E string first, followed by the rest of the strings. This is just an exercise to get you used to playing the E minor chord in a rhythm. Think of it that way.

Otherwise, when you play an E minor chord generally, you will strike all the strings using one motion.

-Billy