I’m unfamiliar with the books, but it sounds like the one S3 will be based on is another solo story.
I wonder if it would have been better to have S2 be another story of Reacher on his own in a new place (and meeting some new allies), and save the Special Investigators reunion for S3.
The team-up dynamic might have been better served as a switch up/refresher if used a little later in the series.