The practicalities of wiring single-core cables through lengths of Flexible Metal Conduit that are longer than about 1m could be an concern and using a draw wire will usually prove to be almost indispensable for this task.
There is no restriction on the length of run of flexible conduits1 but specifications for particular jobs may give a maximum length.(More questions of Flexible Conduit, welcome to contact us for answers!)
An important consideration when installing longer runs of Flexible Conduit is the general appearance. Even with the use of a draw wire, it may be necessary to lay the flexible conduit straight out on the floor to thread the cables through it, prior to installing the conduit in its final position.