I've heard using bleach is an effective means for preventing sewer/lateral clogs. Is it more effective in certain circumstances, tree roots, grease, other clogs.... How much is best to pour down the floor drain, how long should it sit there before being flushed out, and how frequently is best?
Do not use bleach if you're on a septic system. Using bleach for this purpose would not nearly be as effective as using a good enzyme-based, non-caustic drain cleaner such as DrainCare.
An enzyme-based drain cleaner will not harm you, your fixtures or pipes, but it WILL dissolve organic gunk, such as hair, soap scum, food particles, grease, etc. You just run warm water, pour in some DrainCare and let it eat overnight.
Then you flush the drain(s) down the next morning with hot water. I usually start this with a kettle of boiling water, and then let the hot water only run until the drain runs free.
For roots, there are several products to use, such as flushing a few cups of copper sulphate crystals down about three times a year.