Our group uses the Hobbs, and yes you find that a one hour cross country flight (start, taxy, run up, take off, land, taxy to parking, shutdown) costs about 1.3 on the hobbs due to the ground time, and this is quite normal at many places I have flown. However on long flights the differential between hobbs and flight time (or tach time) gets less, so if you did a 3 hr leg, the hobbs would read 3.3 hrs.
We could of course charge "flight time", but if we did we'd have to up the hourly rate from about £65 per hour Hobbs to £80 per hour flight time. Swings and roundabouts really, the little bit extra in the pot left over from charging Hobbs time helps keep the aircraft account healthy and the "hourly costs" down.