I guess it depends. It depends on their purpose -- if they want to strengthen their relationship? or if this is their way of escaping from it?
If their reason is to strengthen their bond by sacrificing a bit for their future, it still depends on the couple if they want it to work. It depends on each one of them if they are willing to work it out. In a long distance relationship, there are important things that a couple needs to put on their minds -- communication, trust, loyalty and honesty. So far, for me those are very very important, in no particular order.
Communication is a must. It is a way of letting their partner know what they're doing (if they are busy, on work hours, or whatnot so that the other party will know and understand what's going on because of the fact that they can't see or be with each other) and how they feel (if they're happy or lonely, or if they need to be comforted because of a long day). Nowadays, we already have a lot of means for us to communicate with other people especially to our loved ones. So there should not be a problem of making some time to communicate with each other, unless you don't have time to do so..
Loyalty, honesty and trust must be present at all times. And these should not be taken for granted cause it can make or break the relationship. Being loyal and honest to our partners, and not to be involved in micro-cheating can bring peace to the relationship, especially if you're on LDR 'cause you don't want to lose the trust of your partner. Having doubts, no trust, dishonesty, and not being loyal -- these are poison in a relationship.
So to answer the question if long-distance relationship works? It depends -- if the couple want it to work to strengthen their bond, or to escape and break the bond.