I know of 2 locations that used to consistently have random encounters one was star light drive and another was close to the Institute crater have these been changed? They no longer seem to appear any more.

In past games, it was RNG for most of these happening. So, you may be on the thin part of the RNG number table.

Well I do have impression that random encounters for certain locations can "run out". There is for example crossing south-east of Concord, just before Drumlin Dinner. Right at the spot where you first encounter Trashcan Carla. After some time, random encounters just stop appearing there. I had it happen in several playwrights. I play without fast ravel, so I trespass these random locations often.

Some encounters are repeatable, some can occur only once. If location have no repeatable set for itself, then theoretically it indeed can run out of encounters.

Bye they way, there are lot of these random spawn locations all over.