Maturity levels should not be skipped. Each maturity level provides a necessary foundation for effective implementation of practices at the next level. Higher level practices may be performed by organizations at lower maturity levels, but have less chance of success (especially during crises) without the discipline provided by lower level practices and the effect of innovation can be obscured in a noisy process.
CMMI identifies the maturity levels through which an organization should evolve to establish a culture of excellence. Because each maturity level forms a necessary foundation on which to build the next level, trying to skip maturity levels is usually counterproductive.