I do my strides a very prescribed manner as I have a long powerful stride but my cadence is low. I try to do this weekly to a maximum of 20 sets, although I have been known to miscount and get up to 23 doh! although today I did 6.
I count every left (could be right) foot strike on the ground starting at 0, the aim is to get 30 left foot strikes in 19 sec. This then adds up to the magical 180 steps per minute that all elite distance runners run at or above. The recovery time varies but your breathing should be fully recovered, generally between 40-60secs, but it can take longer and you shouldn't scrimp on recovery.
It is not about speed or distance covered in that time simply about leg turnover. Although I am always surprised by how fast you end up running.
When you start running these sessions it is best to start on a slight downhill to make sure you turn your legs over easily, although I can now run them uphill, in mud...well anywhere really.