Setting aside porn, the answer is something along the lines of "it depends."
Gang-banging is a fetish with its own terminology and protocols. The "center" is the individual focus of attention in a gang-bang, while the "bangers" are those focusing sexual attention on the center. For some gang-bangs, there is a high level of organization, including screening/vetting, rules and protocols, often including a facilitator or two, who aren't necessarily direct participants as a banger. For large events, there are sometimes fluffers, providing manual and oral stimulation to the bangers while the center is occupied.
The experience as a banger varies on many dimensions. In organized events, the facilitators will monitor the bangers, coaching or mentoring, making sure whatever rules there are get followed, like use of condoms, avoidance of certain acts, etc. In large groups, while the center is fully occupied, an "idle" banger may be watching, stroking/masturbating, or being fluffed, if there are fluffers.
Some venues and events tolerate, even encourage bisexual male contact during the event, where the bangers not engaged with the center are performing oral sex on one another, engaging in mutual masturbation, or cock-on-cock activity. Some events/venues prevent or discourage bi male contact.
It is a different experience to be a random banger, with no relationship or connection with the center, than to be a banger or facilitator who's partner is the center. The first time I saw KK in a gang-bang, I was totally overwhelmed emotionally. I was able to perform, but the intense experience of seeing my wife impaled on cock after cock, sucking, being groped was a blend of revolting, incredible erotic, and disturbing.
As a banger, you're just there to provide stunt cock services. The expectation is that you'll be able to get hard, stay hard, and avoid premature ejaculation, to service the center. It is always surprising to see how many men can't meet one or more of these expectations.
As a facilitator, you're there to help the center, keep the center safe, healthy, and provide support. The focus is caregiving, before, during, and after the gang-bang. In that role, I find myself aroused beyond belief, but not being a direct participant means denying the urge to be one of those hard cocks servicing the center.
