Top,
There are a fair number of instances when a heavy favorite is so overweight in a multi race pool, that at best, you get neutral value, sometimes negative(parlay less chop in all legs)This can even happen at major venues with good sized multi race pools.The pick 5/6 pools at the majors seem to be immune from one leg of an overweight favorite, pick four not so much,rolling pick 3 and DD,not at all.
Except if you are jamming money for rebates, the above is the single most relevant issue in staying out of multi race pools at small venues. Illiquid pools the 800 lb gorilla in the room for anyone trying to beat the game via those pools.
Mike