There have been threads on this topic in the past where many admitted to doing this. Gina's mother always told her that when you write a letter, you count an hour. Never mind that it's to your grandmother, you only cite a single scripture, and it actually only took you 15 minutes. 1 letter = 1 hour.
There's a very amusing book that suggests anyone can be an elder. One of the "tricks of the trade" is lying about field service. It also mentions your "show up, say you have a bible study, leave and go home" trick. Worth reading if you can find it: "From Publisher to Elder in Six Months"
I didn't THINK I cheated on my time until I started reading this thread. I sure did chitchat, I sure hoped to be loaded into a 7-person car group to do rural territory (where you preach 5 minutes out of every hour), I took coffee breaks, I delighted in return visits on opposite ends of the territory. So yeah, I cheated my sincere little a$$ off.
Almost makes me wanna go back just to see how far I could go gaming the system like this! (but... not quite. :-) )
All this raises the question: How much of their much-ballyhooed "billion hours of preaching" is actually spent talking to a non-JW? 5%? 10%?
Dave