  A novel comparison between the data and the theory is proposed for the
nonmesonic (NM) weak decay of hypernuclei. Instead of confronting the primary
decay rates, as is usually done, we focus attention on the effective decay
rates that are straightforwardly related with the number of emitted particles.
Proton kinetic energy spectra of $^5_\Lambda$He, $^7_\Lambda$Li,
$^9_\Lambda$Be, $^{11}_\Lambda$B, $^{12}_{\Lambda}$C, $^{13}_\Lambda$C,
$^{15}_{\Lambda}$N and $^{16}_{\Lambda}$O, measured by FINUDA, are evaluated
theoretically. The Independent Particle Shell Model (IPSM) is used as the
nuclear structure framework, while the dynamics is described by the
One-Meson-Exchange (OME) potential. Only for the $^{5}_{\Lambda}$He,
$^{7}_{\Lambda}$Li, and $^{12}_{\Lambda}$C hypernuclei is it possible to make a
comparison with the data, since for the rest there is no published experimental
information on number of produced hypernuclei. Considering solely the
one-nucleon-induced ($1N$-NM) decay channel, the theory reproduces correctly
the shapes of all three spectra at medium and high energies ($E_p \geq 40 $
MeV). Yet, it greatly overestimates their magnitudes, as well as the
corresponding transition rates when the full OME ($\pi+K+
\eta+\rho+\omega+K^*$) model is used. The agreement is much improved when only
the $\pi+K$ mesons with soft dipole cutoff parameters participate in the decay
process. We find that the IPSM is a fair first order approximation to
disentangle the dynamics of the $1N$-NM decay, the knowledge of which is
indispensable to inquire about the baryon-baryon strangeness-flipping
interaction. It is shown that the IPSM provides very useful insights regarding
the determination the $2N$-NM decay rate. In a new analysis of the FINUDA data,
we derive two results for this quantity with one of them close to that obtained
previously.
