CRM 365 Behaviour of the save button.

Hello ALL Experts,

I need to know is it default behavior of CRM 365 that ,

I have Business Process Flow on custom entity having different stages ,

when i click on Next Stage button , the bottom right corner button seems to be automatically saving.

My query :-

when we click on Next Stage the save button automatically saves it, what actually it's doing , is it saving the whole form  again, or something else happening there.

if it's saving the whole form again then one custom JavaScript code has been written on form save which does the updation of the field on the with stage name.