You arrive on set, get everything set up, take the camera out of your bag and after the first 10 shots, when you really start shooting, the battery goes dead. You panic. You are completely thrown, even if you have a spare battery. It's obvious that you should charge the battery, but you can't say it enough. It has happened to me often enough, especially because I have said spare battery with me. It's just stupid when it's empty. So it's best to be consistent and put the batteries in the charger immediately after a shoot, then you won't have any problems with the flow.