After a getting a used Canon 50D two years ago, I just discovered there is a neat preset available. When I use it for layout pics, I set it for an aperture of 22 for maximum depth of field, ISO 1000 to shorten exposure time, and a custom white balance to correct color. Invariably, when I go outside or take other kinds of pictures, I forget to reset the camera for more general purposes. So I usually mess them up, then when I go back to layout pics, I forget one or more settings. Now I find the camera has two presets. As the manual states, "The current camera settings can be saved under the Mode Dial's <C1> and <C2> positions." Now my grab and go settings are what they were the last time I used the "Creative Zone" and all I have to do is change to <C1> to take layout pictures. Ain't technology wonderful?
Custom functions are cool! My son kinda learned this the hard way this weekend. His camera battery still in the bag, and the body was set for something not conducive to daylight railroad photography, and the situation presented itself to bag the movement of White Pass & Yukon's newest loco, headed west thru town. He missed the shot because his settings were not ready, and soon learned why it is wise to always leave your camera settings ready for the shooting you do most often (without sufficient time to recheck them). I learned the hard way too many years ago....