I guess that fact that you don't want to stop is that getting to that level is an infrequent event. More often you are out of the zone rather that in it. Ask yourself that after a sustained period of being in the zone, how do you feel when you finish?
- Elated, exhausted, in need of rest and perhaps a reward.
- You should be feeling pleased with yourself and rightly so.
- You have achieved a great deal more than normal probably without distractions and this is true productivity.
- You are probably running in overdrive.
The key with the Pomodoro Technique is that you are working at a sustainable pace. By having regular breaks you keeps you overall productivity up. By managing interruptions you get defined segments of true productivity. The technique helps when you are not in the zone. When you get into the rhythm of the Pomodoro Technique the breaks are part of your flow. The symptoms are like the zone but longer lasting. You may not get as much done over a day but over a week, a month the results will begin to show.
You are the tortoise.
Another way to look at it is weight training. A weight trainer does not build his muscles by lifting a 200kg weight for 5 mins. He does a set of reps and then rests his muscle before he does another set. If he does too many he will tire himself and lift less.