7f lines for a mile race

[Latekick]

I've been handicapping Saratoga mainly this summer so far and Monday i found myself running into a problem that i have often run into this summer. Horses with impressive races going 7f in a race carded today for a mile. I remember reading somewhere on this website a while back that its okay to use a line if its within 1 furlong of today's distance. Well i found myself being somewhat inconsistent when trying to use a 7f race as a line for a two turn race today. My question is, should i not use any 7f races if today's race is a mile, even if the horse has a few races going 1 mile but they are sub par and they have a nice 7f race within 3 of the last comparable?
My question plain and simple is, should i be using lines at 7f for a 1 mile race?