110%..........now wouldn't that be nice!!! I worked 10 races on Saturday, averaged 95%, and only won on half of them, but still had a winning day.

I used to work for one of the old style figures bookies, probably the best in the game.

I find myself being somewhere in the middle of the options you've given.
I do some form study, I look at gear changes, do rating's for the better races, and then try to lay accordingly.
When I work a race I always try to make the fav the worst result. I don't lay horses @ 10 or more, unless I've rated them as no chance. I try to have no losers, but when this doesn't work, I try to have no more than 2 losers. In Danewin Lodges race, he was the only runner I didn't lay.
1 break even, 2 loser (fav), 3 winner, 4 winner, 5 winner, 6 small loser, 7 a skinner. I gave 1,6 & 7 no chance, and laid accordingly, except 7 which was over 100/1. I did well this race achieving 103%.

I don't know that there is a set way of winning, everyone has a different approach, and what works for one, may not work for another.