I just read Aziz Ansari's book Modern Romance, and he brings up an interesting scientific study that was conducted in relationship to timetables for texting. What they did in essence was give rats rewards for when they hit a button. When the rewards came immediately, the rats took for granted the rewards. When the rewards came sporadically the rats would overinvest in hitting the button to get another reward.

I am paraphrasing here but in essence what the data concludes is that playing waiting games with texting works. It gets the other person to think about you more and to invest in you more. While texting immediately leads to your texts taken for granted.

There are obvious limitations to this. If you wait for days on end, the other person will give up on you and move on. But waiting hours is an effective way to get the other person to want to text you even more.

There is another reason for adding excess time between texts. It conditions you to be someone who is not needy and waiting around for a text. When I shifted my mindset to only texting girls sporadically and with hours in between, I ended up having shorter and more meaningful text message interactions. No longer was I being bogged down in excessive text message conversations.

The only exception I would make to this rule is when you first meet the girl and get her number. Text her immediately. That way you have her details in a text message thread, it is the polite thing to do, and you don't forget to text her later. Also she remembers you while you are still fresh in her mind.