If a Christian sincerely uses this as a strategy they are truly misinformed on how their religion actually works. While it's true that pretty much every christian flavor believes that faith in Jesus Christ alone saves, and good works are not at all required to be saved. A sincere faith in Jesus Christ will be evidenced by doing good works. This is believed by protestants, Catholics and orthodox alike. The way this works out is that if you personally are not dedicating your life to doing good works according to your ability, your faith in Jesus is not sincere. And if your faith is not sincere, you're not being saved.

The same is true when it comes to sins. If you truly regret your sins you will be forgiven for those sins. But there is no way to cheat on this. God can read your mind and god understands you and your thoughts better than you do yourself. So simply thinking in your mind on your deathbed that you regret all your sins will not save you. You have to sincerely regret all your sins, and not only because those sins will keep you from entering into heaven, you have to regret those sins for their own sake.