I've had the same set on my bass since they first came out. While playing a song with a lot of low B I noticed the low B sounding like it had lost some of it's oomph so I decided to put on a fresh set. That would be about 16 months for one set.
I just tried the cobalts 10 to 46 on my Strat Plus Rosewood neck. Been using regular slinkys for a long time, didn't like the tone of the cobalts on the Strat, too metellaic a narly type tone. They're louder and might work on my Les paul but a won't be using them on the two standard strats. jmp