Thank you all so much for the thoughtful responses. My initial attempt to use it rather reminds me of trying to work out at the gym, where the skill bonus is halved instead of doubled. That was with a rabbit hole, and since then, I've tried it with a self-employed career, and it does seem to be helping.
A little update/additional info in case anyone is interested.
This potion was da bomb for a sim working the Ghost Hunter profession. He was already at level 4 logic when he first started the career, which was on a Friday during normal work hours, so there were no jobs generated that day. He took this elixir and went to the library to read logic books, and made rapid advances in the career, maxing it over the weekend without ever having done a single Ghost Hunting job.