[calm01]

GIB often appears to give partner a ruff.

GIB often appears to abandon giving partner a ruff when one of the opponents can also ruff.

If true this means GIB is unlikley to give partner a trump promotions or even an over-ruff.

Does GIB try for over-ruffs and/or trump promotions?

[barmar]

GIB doesn't think in terms of specific strategies. Its defense is entirely based on dealing a bunch of hands consistent with what it knows from the auction and previous plays, performing double dummy analysis on each of them to see what happens with each legal play, and then choosing the play that has the best expected result across all the hands. It does this from scratch for each trick, it doesn't "plan" the defense.

If enough hands with a promotable trump show up in the sample hands it deals, it will try for it.

[calm01]

I appreciate the clear reply.
In that case more simulations are required to enable the possibility of a trump promotion or over-ruff to emerge and to be considered.