I've been thinking a fair bit about Luke's historical knowledge. I have been focused upon Acts, but as I am convinced that it was written as the sequel to Luke's Gospel I realize that I must think about both works together. When I do I note something of interest. There are a number of events or situations narrated in Luke-Acts that we find independently attested elsewhere: the death of Herod Agrippa, the expulsion of Jewish-Christians from Rome (although this is a bit more controverted than the others), Gallio's proconsulship in Corinth, Felix's and Festus's respective tenures in Judea. Conversely, we have a number of places where Luke seems to make errors: the census of Quirinius and the famous reversal of Theudas and Judas in Acts 5. I've been thinking through what to make of this combination of apparently solid historical reporting and probable error, and as I do I notice what is possibly a very interesting pattern.
The events or situations about which Luke is fuzziest occurred decades before his primary narrative. Conversely, Luke seems best informed about events from c. the mid-40s through to the early-60s. Interestingly enough, the largest cluster of events or situations of which Luke is best informed are situated after the first of the We-passages. With this data in mind, I would like to propose a simple explanation for why he tends to be more accurate during the 40s through early 60s: that was the period in which he himself flourished. He is best informed about this era because he lived through it, as an adult in the prime of his life. It doesn't follow of course that everything he reports in those later chapters occurred, or as described (in fact, there is at least one narrative in that latter part of Acts in which I would argue Luke is demonstrably confused on the matter that he reports, namely his description of Apollos and the twelve disciples in Ephesus, described at the end of 18 and beginning of 19). Neither does it follow that everything he describes earlier confused or mistaken or wrong-headed. It does suggest though that in these later passages his relationship to the material has changed, from something like what we might call an archivist to perhaps something closer to an embedded journalist.