Actually I was just thinking that I did them that way.. it has been too long.. it could be that I didn't do them for 30 s or 60 s but for longer periods.
One thing I certainly tried to do a couple of times, was to try to go as fast as possible a few times.. something you can't imitate on a road bike..
I will go out and get myself a cadence meter again.. my cadence slipped down considerably.
It is good for everyone, but especially for the weaker cyclist to work up to a higher cadence when you don't have the strength to push big gears..
Speed = gears x cadence.. lower gear & higher cadence means same speed but more efficiency.. well, to an extent of course!