I set mine to the minimum of 15 seconds and that’s what I would also recommend you try.
My thinking is that if the 15 second timeout turns out to be annoying when you’re using the display, you can always increase it. But if it isn’t, then there’s a chance you’ll get more economical use of your batteries.
Setting the display timeout to 15 secs does not mean the display will go dark after 15 seconds. The timer is reset every time you press a button. For example, the timer resets when you are scrolling with the arrow buttons or navigating to a sub-menu. The 15 seconds only starts when you are no longer pressing a button. In other words, it only starts counting down when you are no longer doing anything with the pump other than possibly looking at the display.
It all depends on how you use your pump, I guess. I tend to glance at it most often. The long meaningful stares are fewer and farther between.
Also, don’t forget about pressing & holding the menu button for 2-3 seconds. This puts the pump in “sleep mode” and is a way of turning off the display without having to wait for the display timeout to expire.