BGP Route Dampening

A few things that needs to be explained here:

Why is the penalty value getting decayed every 60 seconds, the article only mentions about one method of bringing down the penalty value i.e. half life which has a default value of 15 minutes. It is mentioned that when half life is reached the penalty is decayed by 50%

EvD: accum. penalty decayed to 526 after 60 second(s)
EvD: accum. penalty decayed to 502 after 60 second(s)
EvD: accum. penalty decayed to 479 after 60 second(s)

I am guessing that this 50% decrease is achieved by incrementally decaying the penalty every 60 seconds.

The other thing that needs explanation is:
Why route dampening is not recommended and how does it impact the route selection algorithm.