I've flown with the seven minutes in Canada a lot. If you fly the minimum of 1.5 or 1.8 laps between stunts you will get fly an extra 14 laps waiting for the engine to quit. That is to say, three laps between stunts doesn't really effect a potential over run.
Well, sort of. Once you start the engine, it is going to run about the same time regardless, so yes, if you put in excess fuel, you will get a bunch of laps at the end. But, and I have been doing this a very long time, no one routinely adds extra laps aside from extraordinary circumstances. From signal to wheel stop, a conventional stunt airplane takes about 6:30 to 6:45 doing the prescribed 2 laps between maneuvers.
There is one difference from FAI to conventional rules, you are allowed to do nominal 1.5 laps between the hourglass and entering the overhead 8, instead of a nominal 2.5. the difference is about 5.5 seconds in terms of pattern length, one lap ,which is in the noise if you are not using a timer.
FAI used to be very touchy about making it if there was even a minor problem starting the engine. Fortunately, and probably inadvertently, when the got rid of the 10 starting points, it had the side effect of not requiring a hand signal, so the timing can start when the engine starts. In fact, you are screwing up if you give a hand signal.
You *do* still have to do a hand signal before start for conventional rules. Forget it, and you get an attempt. Of course you also have 8 minutes.
In any case, if you have 14 laps left over at the end, FAI or normal, you are probably putting in too much fuel. You might sometimes want it in some conditions to allow for repositioning, but as a rule, set the fuel too run 4-5 laps after and have it quit.
Brett