While I'm not a big fan of text/online game, it's sometimes inevitable for me. Fortunately, I have a pretty nice success rate. However, I notice a lot of girls tend to delay their responses for hours or maybe even a day. My question is: Is this a tactic girls commonly use in these situations?

Normally, I'd maybe consider the more negative outlook and assume they're not interested and trying to figure out what to say. However, it usually works out in my favor. Understandably, people are busy so immediate responses are not an option (nor does it need to be immediate). Although, if you have an iPhone, WhatsApp or Facebook, you can see 'read receipts' so you know they've seen what you have to say.

Assuming they're not busy, do girls generally do this as part of their game? Do they do it because they don't want to seem overly enthusiastic? What has been your experience?