Westys, I operated a "cover to Win" system successfully in England for almost 2 years, b4 the crash came at a Cheltenham 4 day meeting without a single winner. I lost everything I'd made and more besides. With the benefit of hindsight I now realise like Davez says its better to have "maximum" that youre prepared to blow in one run, then have reserve banks to fall back on "WHEN" it happens.
Another method of selection that you may like to try out is working down from TAB no 1, take the first last start winner, this produces about 25% winners, its fairly consistent, some of course are favourits but also some at very good odds. Last Sat was not a good day for this one , but thats just it, no matter what method, you will never be consistent all the time.

As Davez says as well, its probably better to take the first one in the pre-post quoted at 4-1 rather than just the 3rd fav.
You could also refine this futher by saying : The first one quoted at 4-1 that is a last start winner. OR you could take the firs one quoted at 4-1 as the basic selection but only include IF a last start winner, all good stuff isn't it?