slow transfer speeds (faster)

Just an idea to speed up file tranfers... if there are A, B, and C paths in a network to pass data, and the bandwidths are respectively 15, 10, and 10 kb/s, I imagine file transfers will seek the fastest path (15kb/s). However if the file was split into 3, and passed thru 3 different paths, wouldn't that be like 15+10+10=35kb/s? Just an amateur asking questions. how are file transfers actually done? and considering gnutella has a lot of redundant files, I imagine transfers could be sped up if one downloads the same file from multiple servlets or whatever they are called. (say, bits located at 0 mod 3 of a file are downloaded from source A, etc.) what do people think, and are there work already being done on these areas?