Hardly. Most prisons, if not all, have aggressive programs to stamp out gang behavior inside via transfer programs, confinement, identification, and rehabilitation. It isn't like OZ, Prison Break, or some other glorified prison movie. Where I worked, I've seen Mexican Mafia, Crips, Bloods, the Haitian Zoe Pounds, Aryan Brotherhood(not a true gang in these parts, as the numbers of whites are rather small and they naturally form together), and a lot of others. They mainly hung out with one another for the company, with perhaps some small-time planning for the Outside. Very rarely, and never from when I've been there, have their been "contracted" hits or planned riots. Snitches are usually targeted before anything, and everyone from all sides would be out to get them. I've had to do a lot of transports to move "snitches" to a different facility or put in protective management. The term Human Warehousing is on the money. We placed inmates categoriacally whether it be sex, possible gang affiliation, location to closest family, custody level, etc....
You need to realize our current prison system is broken. We have over 2.2 million people in jails/prisons. That is Human Warehousing for profit. Private companies, the big ones being Wackenhut and CCA, are getting big business from building prisons and receiving government contracts to run them. In the past, counties and towns would normally shun the building of a new correctional institution as there was the thought that it would be a blight on the area. Now, they clamor for them to be built. Contracts, staff, and inmate families end up moving close-by and ultimately spend more money in that area. Small, petty offenses, such as possession of marijuana, DUI/DWI, civil infractions, Tax offenses, etc...are enough to put someone in jail. There are too many people in jail/prison for non-violent offenses, and that is unacceptable. In addition, it is almost impossible to obtain a job after serving one's time due to their record, and people wonder why recidivism rates are so high.
I like to think of the solution, not the problem. For non-violent offenses, there needs to be a different and creative punishment catered to the individual. It is unfair and absolutely stupid to convict, say, a millionaire and a minimum-wager to the same sentence if both committed something like tax fraud. Something unique needs to be constructed for both. In this case, the judge should force a recompensation program in addition with classes and/or community service. The EOE that employers go by should be spread to those with criminal records, particularily to those with non-violent ones. For those with drug-related charges such as simple possession should instead go into a rehabilitation program. However, I do concede that the criminal justice system is not the end all of itself, as there are societal and cultural problems that lie at the core, but I think a reformation of the system would be a step in the right direction.