I use mostly 8 button KPL's in my home with custom etched buttons. I try to set my scenes on the buttons so that they are clear and concise. I let the automation aspect of things happen on the behind the scenes. Double taps provide extended features that me and my fiance use but not are not necessary for everyday use or for a visitor to need. For example, in our main bathroom, dbl tapping the main button off will shut off the fan and the light. A person visiting would not know that but at the same time, they can simply hit the fan button. I have switched out my bulbs and started using hue bulbs. Throughout my house, I put the same button controls in the same places. The Main button is always in the same spot, rooms with Lamps is marked Lamps with it next to the main button. Scenes start the next level and so forth. I try to keep the important functions at the top so your not digging through buttons to do a simple action.
If the room has a second keypad, I generally will put secondary actions on that. For example, my 2nd kpl in the bedroom has the ceiling fan, hvac presets, etc on it. They are clearly labeled so if you were in the room, even as a visitor you would know what they controlled. Once again standard use is clearly labeled. Secondary use from a double tap is not but generally those are things that happen automatically. For example, my phone chargers button will turn on the chargers manually (i have it on timers also) Double tapping the same button will also turn on the charger for my remote; should that be needed outside of it's timer.