Probably the most destructive “booger in the law” is what is known as concurrent sentencing. When a person is arrested on a felony and released into the public awaiting trial, he can commit endless crimes of a lesser penalty value because he will know with confidence that all of his offenses will be merged into one concurrent term of incarceration. If he is already getting 12 years for a robbery where the victim is injured, he can commit assaults, burglaries, drug offenses galore and he will never do more than the 12 years to which he will be sentenced on his primary offense.
A simple way around this would be to always give consecutive sentences, i.e. if you have a 10-year sentence for armed robbery, and commit a crime that carries a 1-2 year sentence (assault), make it a 12 year sentence. Yet this rarely happens in cases where it matters. Instead, it’s done in purely symbolic cases of consecutive life sentences and the like, where it really doesn’t make a bit of difference.