5 x 800; average time or drop time?

I ran my 5 x 800s this AM.  I went to the track because I am tired of guessing if I am really running 800 or not.  My goal was to keep my two laps at about the same time all five sets.  Didn't work.  I think a one minute variation for a .5 mile run is a little erratic.  At some point I thought I should concentrate on dropping time each set.  That didn't work either.  So I wound up just saying the hell with it, I am just glad I am out here running and 2.5 miles doesn't seem so far to my body or mind at this point!