Narrowing Back Hand Springs

I've been told my arms go too wide on back hand spring. I'm wondering if there are any drills that help with getting arms more narrow or if it simply takes a lot of concentrated practice to get used to it? I think my shoulders are pretty flexible, but maybe having broad shoulders makes it more difficult? I notice in general girls have more narrow back hand springs than guys? Also, what's optimal narrowness, however much your body allows?

Handstand distance should pretty be shoulder width distance.

Some gymnasts go a bit wide but that is for more advanced reasons. For everyone else, approxiamately handstand distance.

Go back and work some bridge kickovers and back walkovers/limbers because it is essentially the movement in slow-mo.

A simple remedy is to tie your arms shoulder width apart and practice them that way. A piece of rope, a tshirt, anything really just to restrict your arms from going too wide.

Theraband on the wrists or around the shoulders (bicep outside) works well.