i notice that the Timer setting appears to have a default value of 5 minutes. Without trying various values, I assume that I can change that default for any installed device by changing that value, with the default for that device only reset. I note that you can change that to any number, but not zero. The ability to set to zero might help understanding of this possible conflict.

I'm using, however, the "auto off after"  setting in the specific device setting.  I assume that since I've set that to 7 minutes the device will shut off after 7 minutes, not 5.  I cannot think of a case where i would want the timer setting to override the auto off after seeing, but I can imagine a case where I would want the device to turn turn on in 5 minutes then auto-off in 7, and that would be the interaction; that the auto off would still implement if set. What is unclear is if I turn the device on and to turn off in 5 minutes will it continue to 7 or stop at 5?  The interaction between the two timer serious is unclear, please explain. I'm not using Smart actions here and do not wish to use them, but they may require both settings to work in context. For me a course matrix of cases and outcomes would be helpful if there are no hard and fast types to his these settings affect each other.