Each way help

Whats the lowest price you would take on an EW fancy ? Lets assume there is a minimum of 8 runners thus 3 or 4 places.

Mine has been as low as 5/2 which at 1/5 the odds returns 3/4 of my total stake when it comes placed. Generally i don't like go go below 7/2. I don't bet like this very often but occassionally when you will get 2 or 3 horses with a chance with the remainder no hopers at 12/1 +. I know at 7/2 you still make a loss but is this a long term profitable stratergy  assuming i don't get too many unplaced ?