The $\mathrm{d}$-block sub-shell is always one shell lower than the $\mathrm{s}$-block and $\mathrm{p}$-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), $\mathrm{d}$-block is never in the highest energy shell, and so none of the electrons in the $\mathrm{d}$ subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?

The d-block sub-shell is always one shell lower than the s-block and p-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), d-block is never in the highest energy shell, and so none of the electrons in the d subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?

The $d$-block sub-shell is always one shell lower than the $s$-block and $p$-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), $d$-block is never in the highest energy shell, and so none of the electrons in the $d$ subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?

The $\mathrm{d}$-block sub-shell is always one shell lower than the $\mathrm{s}$-block and $\mathrm{p}$-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), $\mathrm{d}$-block is never in the highest energy shell, and so none of the electrons in the $\mathrm{d}$ subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?

The d-block sub-shell is always one shell lower than the s-block and p-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), d-block is never in the highest energy shell, and so none of the electrons in the d subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?

The $d$-block sub-shell is always one shell lower than the $s$-block and $p$-block sub-shells. Assuming only the electrons in the highest energy shells count toward the set of valence electrons (is that correct?), $d$-block is never in the highest energy shell, and so none of the electrons in the $d$ subshells would ever count toward the valence electrons.

I suspect I'm mistaken. Am I? If so, where have gone wrong?