in your era,I presume hands for girls was the general rule, if girls got it.
It was in mine, though, as an all-boy’s grammar, caning girls would have taken a bit of doing anyway!
Very few at primary school-I can remember only 2 boys & 2 girls in nearly 4 years-2 pairs of truants. All 4 came back to class biting lips and with hands firmly clenched under armpits,which strongly suggests the hands-you are right about it hurting more.
Let’s face it-your sense of touch is strongest there, so it must be more delicate nerve-endingly. OK, I’ve never tried navigating around for matches and candles in a power cut with my backside to test that, but…………!