Our Aircraft are all fitted with Trakfax Flightmeters which record airborne time automatically. They are reset to zero at each 50hr check then read cumulatively to the next check.
This means that the meter reading at the end of each flight shows the time of that flight by reference to the reading at the end of the previous flight and also shows clearly the hours flown since the last maintenance check. The meter ignores taxying, ground running etc..
For charging and personal logbooks we add 10mins per flight to simulate chock to chock but without charging for the ground delays found at some airports.
The only downside becomes flying an aircraft without one and having to note down all the times....