I think your experience is rather rare. I can tell you from my experience that thunderstorms can pop up quickly, be very intense and then diminish rapidly. I can recall a number of occasions when I have entered a ride such as IASW and the sky was clear. However, during the ride I could hear loud thunder and when I exited the ride I observed that the ground was very wet from a torrential downpour yet the sky was once again clear with bright sunshine. Such rapid thunderstorms are very common at WDW. Conversely, it's rather rare for WDW to have a full day of rain. The don't call Florida the "Sunshine State" for nothing.