My students that use Foreflight for their logbook ALWAYS seem to be at least 0.2 to 0.3 higher than the engine-running time, as determined by me through one of three methods:
1) the Hobbs, assuming it's wired to an oil pressure switch.
2) Using a watch. It's really not very challenging. 1:12 to 2:37 is 1+25, or call it 1.4.
3) Using Myflightbook, which has a superior method to Foreflight for accuracy, called "press the button to start and press it again to stop."
Foreflight is so often over-estimating the time that it seems like intentional logbook padding (whether or not you agree with
@EdFred , I think EVERYONE would agree that if the engine isn't even running, it's definitely not flight time). I don't know what algorithm Foreflight uses for this, but it's so often wrong that in my opinion can't be trusted. Let alone it often tracks the walk into the FBO, drive home, your stop at the liquor store or strip club, etc. It's really terrible.