Flying AA into MAD as IB codeshare, ticketed by IB in premium economy; then transferring to Air Nostrum intra-Schengen. And also the reverse, when returning.

Apparently we get "Fast Lane" but not "Fast Track" through security. Questions: Is this available for transfers both ways, or is it only for passengers originating in Madrid as the IB web page linked above seems to imply? If available, how do we find Fast Lane, and is it worth finding (significant time saving) given that it is not "Fast Track"?

Also our last MAD transfer was maybe 10 years ago, and at that time it helped to stay to the far right in the huge immigration lines, because people there were often redirected into the less-busy EU counters. But now that there are electronic gates for EU passports (but not our US passports, AFAIK, unlike electronic gates in some other EU countries), is that advice to stay to the right still applicable?

Many thanks!