I was a bit busy with an academic work last days, but I would like make a pair of considerations.
I think that a chastity belt have to have a safe secondary shield, and this imply that shield can not have slots. If it has a slot, all we know that all of us will try introduce some things to try to test our belt.
Absolutely all of us. A lot, just to experiment what could us feel, or to test the safety of our belt, but most rebellious will try touch themselves. And even they can not do easily, the hope of reach their goal can make they try, and try creating anxiety.
So, for all girls a secondary shield with holes or slot is not good election.
For hygiene, it is good idea that belt has separate padlock so we can take better showers, and in some moments we can wear belt without secondary shield, (you know, sometimes my sister pinches problems for example).
In other sense, frankly I barely can imagine that parents that love their daughter and want she wear a chastity belt approve she can masturbate. I mean, in my case, I can understand a girl has the chance of choice wear or not wear a belt, but if she decides wear, masturbation, obviously is not allowed. And further, I can not imagine none girl asking it to parents, I guess.
And in addition to first point, secondary shield does not prevent all insertion of flexible objects, and for this is strongly recommended we use thigh bands. They are not a restrictive element, anyway they are and all of us do not like physical effects of them, but a safety element. As we can not separate more than a centimetres our legs, the insertion of objects has to be done with a angle that do not allow stimulate ourselves in bad way. How can I know it? Because all of us have some itching under the belt, and one of the worst effect of bands is reducing chances of can scratch it. 😅