Last weekend was a really busy one for me. I started out the day as a mover, taking heavy totes and boxes from one location to another. I quickly shifted to being a soldier during the Vietnam War era. After about 90 minutes I became an MP in WWII patrolling a hanger. Four hours later I was fighting in a nearby field. Two hours after that I was a civilian eating in an Italian restaurant. I repeated the process on Sunday. To say the least, I was worn out by the time I got home Sunday night.
Obviously, one person cannot be all of these things in reality. I was at a reenacting event in which I had to play several roles. It was exhausting for me and a little confusing for some of the people that saw me throughout the day. The problem is that I have read many stories, including by some best selling authors, that seem to have characters like this. Their personalities seem to jump around in a haphazard, almost unpredictable fashion. The characters are always exactly what the situation in the story calls for, but how many people do you know in reality that mold themselves perfectly into the events of the moment? It is confusing for the reader. Be aware of this as you write. It is easy to make your character be exactly what you need when you need it, but does that pull the character out of the realm of plausibility? If so, you may be wearing your readers out by having your characters wear too many hats, helmets, or hairstyles.