Typical evolutionary timescales in our sample evolving from an inert CO-emitting phase to an embedded star-forming phase traced with 21 μm and eventually to an exposed star-forming phase traced with Hα emission. The feedback timescale t_{fb,  21 μm} is an upper limit in 25 out of 37 galaxies, which are flagged with U. The upper and lower errorbars associated with each phase of the evolutionary cycle are shown as thin lines, with the same color. Galaxies are ordered by their Hubble morphological type.