mobile: is there a general rule to know if I should hide the navigation menus on the scroll?

I am working on an Android application, and I implemented a design behavior to hide the top application bar and the bottom navigation menu when I scroll a list page.

At this time, I simply did it because I could and it seemed a good option for software architecture from a developer's perspective, which I think is often at odds with the UI and the UX.

I have reviewed hundreds of user interface and mobile application interaction designs in Dribbble and I have not been able to discover a pattern when this scrolling behavior is still used.

Could someone provide your decision-making process when it comes to whether the bottom navigation menu should be hidden in the scrolling or persistent?

My application will have 5 different higher level pages that can be accessed from the bottom navigation menu. It is likely that any list on these pages has a maximum of 2 full lengths of mobile screen content, which made me question whether I was really doing the right thing.

Some of the questions I found are below.

  • Is this generally a UI pattern that is best served for infinite displacement applications or does it also have its use for smaller static lists?
  • Should I hide both the top bar and the bottom navigation menu? Or keep the bottom navigation menu and only hide the top bar?
  • I have noticed that many of the really attractive designs have a persistent top bar. Is this a feeling shared by others or is it just me? It seems that it is easier to make a page look good when the toolbar and navigation menus are static, while hiding them only leaves a boring list to look at.
  • Is there a minimum amount of data you need before using this pattern? e.g. I have a page with approximately 15 list elements, which might not require this pattern. However, the search functionality on this page looks for data at a deeper level that can result in 100 articles. Would you implement this pattern for both the list and the search results? Or simply the search results? Or not at all for both cases?
  • With the size of the mobile screens, will this pattern be less beneficial or will there be other advantages regardless of the size of the screen?

I do not really need answers to each of these questions, but I would love to know the thought process that is included in the navigation menus and scroll decisions.