Expressions like '열심히 하겠습니다'.
Aside from the term '열심히 하겠습니다', what are the similar phrases to mean 'I will do my best/I will work very hard'?
I'm not so sure but I have seen on dramas that some higher-ups are tired of hearing that phrase? They respond something like 'You don't need to work hard. You just have to do it right' (please include the translation, thanks)

In a workplace for example, are '수고하셨습니다' and '고생 많이 하셨습니다' can be used either way? (선배-후배 or between 동료)

Question

Expressions like '열심히 하겠습니다'.
Aside from the term '열심히 하겠습니다', what are the similar phrases to mean 'I will do my best/I will work very hard'?
I'm not so sure but I have seen on dramas that some higher-ups are tired of hearing that phrase? They respond something like 'You don't need to work hard. You just have to do it right' (please include the translation, thanks)

In a workplace for example, are '수고하셨습니다' and '고생 많이 하셨습니다' can be used either way? (선배-후배 or between 동료)

Answer

You can also say "최선을 다하겠습니다". Your drama quote sounds quite cliche haha.  "열심히 하는 것도 좋지만 제대로 해야지" or "열심히 하는 게 문제가 아냐, 제대로 하는 게 중요한 거지".  I wouldn't say "고생 많이 하셨습니다/ 고생하셨습니다" or "수고하셨습니다" to a high-up, but to a 선배, 후배, 동료, it sounds great!