I just bought a Lumia 520 and that was my experience. With the battery drain looking like it was only going to last for 8 hours on Standby, I went into Settings and found accuweather and Angry Birds Roost were in the list of apps that always run in the background, so I uninstalled both apps completely. However, I also gave the battery its first full charge to 100% and changed my email sync settings to 2 hours for most accounts.
Since then the phone is still at 100% after 6 hours on standby, and with usage, it looks like it will last 24 hours.