Hi beton unfortunately i don't bet the exotics as i freely admit i don't have the psycological make up to withstand the runs of outs.

A punting mate of mine who bets only the exotics told me that getting the fav beat wasn't the problem getting the fav out of a place was the hard part.

Dales probably right with the field size rule i suspect as well

Another approach may be taking trifectas when the fav is at a large s/price.

Here's some statistical data to back it up.

Fav up to $3.0 38.2% = win 69% = place.( loss= 9.6%) win only
Fav over $3.0 22% =win 52% =place ( loss =17%)
Fav over $4.0 18% =win 45% =place (loss = 18%)
Fav over $5.0 16% =win 41% =place (loss =18%)

betting all fav's all odds
55,162 races
17,172 wins
31% s/rate.
Av tab= $2.8.
Av s/p=$2.8 (That came as a shock)
loss = 12.3%

34,042 places
62% s/rate place
Av tab=$1.49
Loss=8%

If you do the( price breakdown of the fav's) to the all breakdown their may be an advantage for trifecta betting but without monitoring on course
prices i am not sure about the prepost especially with scratchings.

Food for thought i guess.

Cheers
Garyf.