Generally speaking, how often should a late-stage intermediate (who does not compete) attempt a PR single, double, or triple as part of training?
It depends. Sometimes never and sometimes every few months. That said, most of the “attempts” should be RPE 8-9, tops, unless a different programming paradigm is used. In other words, there shouldn’t be any misses.
Would that recommendation change for one who is competing? Or save the RPE 10s for the meet?
That is correct.
What would be the best timing to test a PR for someone going into there 8th week of “The Bridge”
What should be the rep range for a test of a 52 yr old lifter who prior to running the bridge had not tested or done a rep range below 5 in his adult life?
You could test it the week following your last workout on the Bridge.
The program is designed to build towards heavy singles at the end, so you’d be testing a heavy single.