I use both very often. Especially as a custom menu for emulator settings, or in older PC games or games with a lot of Keyboard/Mouse controls, they help me make things far more comfortable with various custom popup menus, or sometimes jumping to a mouse region to select UI options while playing. They are also helpful for games with horrid controls/hotkeys that won’t fitnon a traditional amount of controller buttons. They also help with mouse precision when an analog stick won’t do.

I also use the back buttons a lot. I use the entire Steam Deck and the custom controller settings are basically a necessity.