Depending upon how busy it is and if I am getting on or off, I will just tap and keep moving. In particular if it's busy or I am getting off. More often than not I will then get the beep a second or two later that everything is alright. Boarding, I will do a quick tap but will usually linger long enough for the response from the reader. I don't think there's a need to hold the card to the reader until you get a response. I cringe a little bit when I see people pressing their cards against the readers hard enough to make the card very noticeably bend. I often find that stationary readers (LRT stations) respond almost instantly, which I guess is the difference between a hardwire connection and a wireless connection.