The 2nd pass will almost undoubtedly take longer to process than the first pass, because of how the 2-pass process works in ffmpeg, and the fact you'll be compressing already compressed images again.

The target file size will still have the same maximum possible size it had before. First, how would you constitute the 2nd pass? If you repeat the first pass logic, you'll likely attain a smaller target file, but you'll also likely dilute the overall image quality to some extent. Running 2-pass on capped CRF (aka Constrained CRF) is redundant and a waste of time. Now, take that concept and think about applying ffmpeg's 2-pass model to it.

This forcibly limits the freedom of the CRF algorithm with respect to its upper limit of bits-per-frame. The purpose of which is to constrain/limit the overall file size to a pre-defined maximum. The author's point was to describe 'capping' or constraining the CRF setting by creating a bandwidth ceiling per frame. I'm not sure you gathered the spirit of that article as intended.

Ffmpeg h264 fastes encoding