zatopek wrote:
I suppose it doesn't matter if you go 12 or 12.5 but it is kind of nice to know. But when it is really useful is if you are doing, for example, a w/o on the road like alternating miles 5:40/6:00 or like I said before if you are trying to run a tempo at a set pace. Is it necessary no, but it is quite a convenient little gadget. It has definitely improved my running.
Also because many runners are compulsive about numbers, milage..splits etc. it really feeds into that compulsion.
Honestly, I can't say I'm all that curious how close I was when I call my 50 minute run 7 miles. I can tell pace to within 10/15 sec per mile, so for a 10 mile run it's reasonably accurate.
And as for the tempos, that's exactly why I recommended a HR monitor. That type of training is far more accurately done by heart rate than by pace (5:30 can be my tempo pace one day, and a week later 6:00 could be... HR lets me stay in the right zone and not under or over train).
Any kind of really precise workouts should probably be done on a track anyways, as the GPS simply isn't accurate enough for intervals.