It's not the number of home pages or icons, but the widgets that update information. If you have a clock widget only, then all it does is display the phone time and uses little or no extra power. If, however your widget syncs with your Google calendar and shows current weather, then depending on how often it syncs it could strongly impact batter life and data use. In any case, it will be the widgets to consider if battery life and data use while inactive is the primary concern.