Usually, I prefer to investigate a bug starting from the code rather than the history, if it's possible. In my experience, most bugs have taken longer to reproduce repeatedly than to understand from code. Besides, there's no guarantee that a bisect will land at the right commit if the bug is not reliably reproducible.

But I have been in situations where I had to manually bisect the code because I just couldn't understand how the code could reproduce the problem, and having git bisect would have been a significant help.