My mother always used to tell us growing up that "Prevention is better than the cure." It was a warning that if you don't take the necessary precautions to fix something, or set it up a certain way, you may find yourself in a situation that is deeply problematic, and cause you much grief. It is not foreign to find yourself in deep reflection, thinking if I would've just done this, that wouldn't have happened. You have to be meticulous; showing great attention to detail; being very careful and precise.
This is also true when planning events. Many times during the planning process and day of the event you are going to have to intervene, and/or intercept a particular element that could end up very wrong, very fast. You have to be diligent in being aware of what is going on to make sure you catch anything that could derail your plans and the whole day. Most importantly always armed with a solution for any problem, anything less is unacceptable.
As an event planner, I am the representative of the host, and or couple, and it is my job to anticipate and put out any fires before it gets out of hand. As a manager of events, or if you are a leader, manager/supervisor over anything, you need to do it with tact and finesse, especially when dealing with people. When handling guests, you don't want to offend anyone, so tread lightly.
When you book a planner, you get to enjoy your event without even knowing these things happened. I have had many post-wedding wrap up conversations with couples, letting them know of some of the mishaps I handled. They are always amazed that they never even knew any of what was going on behind the scenes. My response is always, "Great, then I did my job!" It is always better to be proactive than to be reactive. Always remember, every big problem was once a little issue that went unchecked.