For what they are... basically modeling a small circuit at low speeds and low power < 1W they are useful however until one really learns the limitations, High interconnection (pin to pin) capacity. Noisy, Dirty and intermittent connections (I recommend a marine lubricant called LPS) and relatively high supply rail resistance > 1 ohm...
Keeping that in mind, When a circuit works put it in place on a proto shield, re test it carefully to verify that the breadboard values are the real values and go on to the next part. Breadboards aren't meant for permanent and complete projects, they are a medium for Modeling a limited subset of electronics with the understanding that the results may be dependent on values used to compensate for the effects of the breadboard. This includes but is not limited to High Speed anything. Breadboards become real 'unusual' at speeds above 50 MHz. Low Noise anything. dealing with millivolt levels on a breadboard is problematical from several standpoints. High Voltage anything. Any voltage greater than 25 V should be avoided or put on a separate breadboard with HV isolation and finally RF anything including antenna connections, Especially antenna connections.
Finally, LCD backlight currents are really too big for connection to a power rail except at the same place the power does. This helps to avoid the voltage drops caused by the backlight current.
I need to repeat that again because of the structure and properties of a breadboard, twice as many bypasses as would be required on a finished PCB type of construction and this includes soldered proto boards too might not be enough. It's easy and virtually free to put down the footprints in the final PCB design, A little testing will tell you which ones are needed and which are optional.
Bob
{Edit: Funny thing wuz that it all made sense... when I wrote it. RKJ