Preparation for blitz games?

In chess.com I usually just log in and accept the first person challenging me in 5 or 10 minutes blitz. However, I noted that several of my adversaries played already several times against me. Is this a coincidence? Probably not considering how many people are online in this site. Or can it be that these people have a kind of alert and know when I am online, so they can play against me? Not that I have something against this, I just want to know. The question is relevant, as in this way people can really prepare to play against me.  And you, do you prepare before you play blitz against a certain players?

Thank you for your answers!

Tactics my friend. Tactics are key.

From Ian Fleming's novel "Goldfinger", once is happenstance, twice is coincidence, three times is enemy action.  If the same opponent pops up three times you will know, like James Bond did in "Goldfinger", that they're out to get you.  Arm yourself and turn out all the lights in your house.