Most of these factors do not overcome the big disadvantage that fiber splices have in most premises networks, say, the inability to allow easy access to the network for testing or moves, adds and changes. Even long-distance telephone networks use fiber optical connectors at each end of the cable to allow connections to patch panels or network equipment that are often accessed for changing hardware or testing. Testing an individual splice is impossible without using an OTDR, another expensive tool that may not be useful in a premise network with short cable runs. However, fiber optical connector can easily be tested individually, verifying performance before the final network is connected.
Usually, only large premises network uses fiber splices instead of fiber optical connectors, for instance, a college campus runs fiber to every dorm room for connecting students to the campus network. The trade-off is made because the network is not intended to be changed once installed. Each dorm room is to be connected to a main computer room where the electronics for the network resided. Little space is available in each dorm for fiber optic patch panels, making the small size of the splice closures a necessity.
That same reasoning could be used on many fiber optic backbones. If the cabling is simply connecting point A to point B and those are permanent locations, the backbone could be spliced in place and forgotten. If plans changed and modifications were necessary, it is possible to cut out splices, but that is much more expensive than simply moving a couple of fiber optical connectors on a patch panel.
There is one mandatory application for fusion splicing in premises networks, terminating single-mode fibers. All single-mode fiber termination in telco and CATV networks is done by fusion-splicing pigtails on the end of the cable. The reason for this is single-mode termination is a much more critical process than multimode terminations. It requires special techniques with diamond lapping film and a polishing slurry to get a smooth finish on the end of the fiber that will produce low loss and back reflection.
This process is extremely difficult to control in the field, especially when hand polishing, which is why most single-mode terminations are made in factories using polishing machines. Single-mode connectors in a premises network must be high quality, therefore, it is recommended that all single-mode terminations be made by an experienced splicer with factory-made pigtails.
It is wise to understand fiber splices and consider their applications even in typical premises applications where fiber optical connectors are routinely used, making the final decision depend on the usual factors: cost, installation ease, and performance.