  Many new models of wave turbulence -- frozen, mesoscopic, laminated,
decaying, sand-pile, etc. -- have been developed in the last decade aiming to
solve problems seemingly not solvable in the framework of the existing wave
turbulence theory (WTT). In this Letter we show that very often the reason of
these discrepancies is that some necessary conditions of the WTT are not
satisfied: initial energy distribution is not according to the assumptions of
the theory; nonlinearity is not small enough; duration of an experiment is not
sufficient to observe kinetic time scale; etc. Two alternative models are
briefly presented which can be used to interpret experimental data, both giving
predictions at the dynamical time scale: a) a dynamical energy cascade, for
systems with narrow initial excitation and weak and moderate nonlinearity, and
b) an effective evolution equation, for systems with distributed initial state
and small nonlinearity.
