Does Bent's Rule only apply to molecules where there is hybridisation?

I would just like to ask if the pre-requisite for using Bent's Rule is that the bonding in the molecule involves hybridised orbitals.

I was thinking of why the bond angle in hydrogen sulfide (~ 92 degrees) is larger than the expected 90 degrees. I thought that Bent's Rule would be able to offer a good explanation for this as the s orbital character concentrated towards the electropositive hydrogen atoms results in stronger bond pair-bond pair repulsion, increasing the bond angle. However, I realised that my entire argument may fall apart if Bent's Rule does not work for bonding involving unhybridised orbitals.

• @TanYongBoon The s-p gap in atoms of the third period and below is in most cases too large for s and p orbitals of the same atom to mix in molecular orbitals. The hybridisation approximation breaks down at that point. That is one of the reasons for the different angles in $\ce{NH3}$ versus $\ce{PH3}$, see here. – Martin - マーチン Nov 17 '17 at 2:59