I always try to follow the 2/3 rule when texting. But I want to know who should have the last word in a text exchange.

Example:

My main girl wanted to hang out with me today, but I told her I was staying home to finish up some work.

She says that she is going to go to the museum with her friends then, and she wishes me good luck in finishing my stuff. (with a nice smily face and everything)

I usually try to not be the person sending the last text because it interrupts the 2/3 flow, keeps them hanging on just a little, and helps demonstrate a lack of neediness. But in this situation I feel like rewarding her with a short "Thanks cutie ;)"

What are your guy's thoughts on this?