Provides guarunteed throughput (as fast as the disk can manage). Very effective when sizes of files known in advance (e.g. CD-ROM, or shrinkwrapped software), requires little overhead (just a start block, and a block count for each file).
Impractical in general case, since files are required to grow (problem of external fragmentation).
Used in some systems (e.g. some versions of UNIX) for small files. Larger files (than, say 56K), use some other scheme which distributes the blocks of a file around the disk sectors.