Talking with Pierre when I was in France he recommended a 25-30min (or 600 vertical meters, whatever came first) hard climb once every 1 or 2 weeks, while Javi said he would do 13- 15 mins climbs like this.
The key is doing it on the same slope or hill each time so you can gage your performance. It's a little bit like a race against the clock in some ways.
I used MapMyRun.com again for the Helicopter Hill run.
In winter we did similar "tests" like this up Porters and Cheeseman ski areas and once all the snow has gone I will do similar runs up the Avalanche Peak Track on Arthur's Pass! This is a really good one, one of my favorite runs. My fastest time from the AP DOC center to the summit is 55mins and I have heard of folks doing it in the low 50's. A sub 50min effort would be pretty huge..........