I always wondered about this, but imagined that a slight detune would give rise to harmonic richness, rather than have anything to do with decay. Obviously, the strings need to be close-enough that the period of any “beats” (volume variations due the the fundamental harmonics shifting in and out of phase) is long enough such that that they are non-audible. Triads of strings would be less susceptible than pairs, I imagine, too.
Thanks.
