FWIW I put Newtone strings on my Martin D28-S after reading the recommendations on here (probably by Giok) and have to say that they have lasted longer than any other strings I have used.

Coming up three months now, and they still sound bright, with true intonation, all the other strings (including D'Addarios )would be dead in the water by now.

That said, it should be noted that for professional players, the length of time a string lasts is irrelevant, as they will change their strings with a greater frequency than inspired amateurs.

Martin Simpson, for example, uses D'Addario strings, and restrings his Sobell guitar with a fresh set, not only before each performance, but also during the interval.

He does get them for free, of course ...