Change and decay of one's own body. How fast is it?
With vipassanā-ñāṇa you can recognise this change perhaps not to the clarity as in the Abhidhamma.

In p 39 of Process of Conciousness and Matter by (Aggamahāpaṇḍita) Bhaddanta Dr. Rewata Dhamma (Writen as a supplement to Comprehensive Manual of Abhidhamma), gives an idea at what rate phenomena arises and passes away.

For personal practice if will be sufficient recognise:


Arising
Passing
Change, i.e., what has arisen is what has not arisen before 


Also see my other answer on similar subject matter: https://buddhism.stackexchange.com/a/12392/295

Following two articles by Piya Tan might be of interest:


Dhamma and Abhidhamma
The Radiant Mind