Subcaudal Scale Depth

I recently purchased a probing set and wanted to verify the sexes of my snakes. I probed my normal to a depth of around 5 scales, I did this twice and came up with the same number.

I also probed my female which only had a depth of 2 scales and I probed my male pastel which had a depth of 8-9.

I wanted to verify my normals sex, but he falls right in the range of female to male (2-4 female and 6-10 male).

My question is how uncommon is it for a female to probe that deep or a male that short?

Would you be able to pop the animal far enough to see the scent glands if it were a female? I'm just assuming the normal in question is old enough to control the popping from really affecting him.

5 is generally considered a female.

But in all cases, if you can't determine it by probing, pop to confirm.