1, He not only studied hard, but also joined many extracurricular activities.
2, Not only did he study hard, but he also joined many extracurricular activities.
I was taught that sentence 2 has a more advanced grammar structure (which is called inversion) and therefore will generally help receive a higher score in language exams.
Is that so?
In order to formulate this inversion structure, sentence 2 has to contain an additional “he”, which is a little bit cumbersome. The increase of complexity seems to be offset by the decrease of brevity.
For shorter sentences, such as “Not only can she sing, but she can also dance”, I feel this well-intentioned upgrade backfires. “She can not only sing, but also dance” should be more concise.