It's crucial for an agency to have a high crack rate, since 'going again' on a brief effectively means you are doubling your costs.
One of the many smart initiatives at BBH London is to carefully monitor the agency's crack rate. They realise their best chance of making money is to crack briefs first time - this is also strongly correlated with high levels of client satisfaction. Accounts where it is regularly not happening, can expect an inquiry.
But if you're a creative, the situation is more ambiguous. Superficially, a super-high crack rate may seem great. You will be seen as extremely reliable.
On the other hand, as the old saying goes... if you're not failing occasionally, you're not trying hard enough. The only thing that will give you a long-term career, as a creative, is occasionally doing great work. And great work is hard to sell. So a 100% crack rate could be a warning signal, that you're playing it too safe.
Some creatives are more comfortable being useful, cracking every brief, and hoping that one or two will turn out great. Others prefer to take a wild swing every time, and don't mind that they often strike out, knowing that occasionally they will bust the piñata wide open and be showered in candy.
Which is right? Whichever you're more comfortable with, I guess. Though it has to be said that option 2 are a dying breed.