You do! You do so by accident though, with your innocent mouse and scroll wheel.
Here's what happens. Let's imagine you are starting a new floor, or roof or wall, something, and Revit pops up a Save Reminder. It always does when are starting something time consuming doesn't it? You also happen to decide to zoom in or out using the scroll wheel on your mouse.
Timing is everything!!
At the same time you do this, the save reminder shows up. The focus shifts to the Drop Down list of time intervals. Since you are spinning your wheel expecting to zoom you don't notice that you momentarily altered the interval!
Users of Revit MEP have changed their selected pipe or duct for a similar reason. I mentioned this in another POST.