Sounds odd but I suppose that if the airport is big and or busy (mine has 11,000ft runway and lots of big jets) the taxi time coule be weird - so one would tend to benefit (I have had a 0.9 on the Hobbs but w/off to w/on of less than 30 minutes; so one would "win"
A smaller less busy airports with shorter taxi distances one would tend to lose.
The real reason for the w/off w/on thing is to get the benefit of the hours count for 50/100 hour checks - one only records w/off w/on (the tach takes care of engine times) probably delays the 50/100 by 5 to 10 hours overall.
That means for a busy renter their plane is more economic - so even if you seem to lose by a few minutes, you are benefiting form the renter's lower costs in the rate to which the hours are applied.