Been using Nanowebs on my 6, 12 and mandolin. Like any guitar strings the length of 'serviceable brightness' varies from set to set. Had a set on my 6 string that lasted for well over a year. The next set lasted about a month. :-( Should'e never changed them. Mandolin and 12 strings vary according to amount of use.

The main difference I hear is that I used to kill a set of strings every night I gigged. Now I get alot more time out of each set. Especially, when playing plugged in as there's a 'false' brightness that comes w/using a transducer/Joe Mills mic combo. One simply rolls off the treble a bit to get a solid acoustic sound.