The different cables all have strengths and weaknesses.  Single-mode cable is frequently used for very long distance cable runs.  It's not unusual to use a 20KM piece of single-mode cable.

fibre optic installation jobs

But, the hardware to support single-mode cable is traditionally more expensive.

Multi-mode fiber doesn't work over such long distances, but the hardware for it is traditionally less expensive.  Multi-mode 62.5 and multi-mode 50 are commonly used with LED based

communications hardware.  10GB multi-mode, which is also 50 micron, is faster than the other types of multi-mode, mainly because its been designed to work with faster,

laser based communications hardware.