trading certain times of the day ?

["hans esser" <he96@xxxxxxxxxxxxxx>]

hi,

Im thinking wether limiting trading to/or excluding  certain times of the session 
maybe better for various reasons and would like to hear what INTUITIVE and 
SYSTEM traders think about it:

IMO special times in S&P :

first hour
first 2 hours
last hour - after bond close

Would you recommend to EXCLUDE those times, especially the first hour ? 
(after a first trend has establiched ?) or JUST trade the last hour ?

Im not trying to be even more lazy but CONCENTRATE better on SAFER (if 
there is such thing) periods of the day ?

thoughts ?

thanks
rgds hans