  Nuclear magnetic resonance (NMR) provides local, bulk information about the
electronic properties of materials, and it has been influential for theory of
high-temperature superconducting cuprates. Importantly, NMR found early that
nuclear relaxation is much faster than what one expects from coupling to
fermionic excitations above the critical temperature for superconductivity
($T_{\rm c}$), i.e. what one estimates from the Knight shift with the Korringa
law. As a consequence, special electronic spin fluctuations have been invoked.
Here, based on literature relaxation data it is shown that the electronic
excitations, to which the nuclei couple with a material and doping dependent
anisotropy, are rather ubiquitous and Fermi liquid-like. A suppressed NMR spin
shift rather than an enhanced relaxation leads to the failure of the Korringa
law for most materials. Shift and relaxation below $T_{\rm c}$ support the view
of suppressed shifts, as well. A simple model of two coupled electronic spin
components, one with $3d(x^2-y^2)$ orbital symmetry and the other with an
isotropic $s$-like interaction can explain the data. The coupling between the
two components is found to be negative, and it must be related to the pseudogap
behavior of the cuprates. We can also explain the negative shift conundrum and
the long-standing orbital shift discrepancy for NMR in the cuprates.
