Whether you have a shakey second serve or an unreliable backhand, you can still be successful if you learn to protect your weakness or for some, weaknesses.
No matter what your skill level is, every player has an Achilles heel. And sometimes, even with steady practice and effort, there’s only so much improvement one can make. The fact is nobody’s perfect. The key is to make do with what you’ve got and try to work around the situation. More often than not you have had this weakness for a long time and technical advice will help to improve this weakness however in the meantime you still need to win matches so protecting it until improvement is achieved is a good option.