Yes.
Unless verified by multiple well-documented, independently verifiable sources -- all 'first-hand accounts' are to be taken with a grain of salt.
Same as any modern news story.
And I did not realize that anyone disagreed. I find that discouraging.
Ahhh... The caveat!
Professor Sherwin-White is not a theologian; he is an eminent historian of Roman and Greek times, roughly contemporaneous with the NT. According to Professor Sherwin-White, the sources for Roman history are usually biased and removed at least one or two generations or even centuries from the events they record. Yet, he says, historians reconstruct with confidence what really happened. He chastises NT critics for not realizing what invaluable sources they have in the gospels. The writings of Herodotus furnish a test case for the rate of legendary accumulation, and the tests show that even two generations is too short a time span to allow legendary tendencies to wipe out the hard core of historical facts. When Professor Sherwin-White turns to the gospels, he states for these to be legends, the rate of legendary accumulation would have to be 'unbelievable'; more generations are needed. All NT scholars agree that the gospels were written down and circulated within the first generation, during the lifetime of the eyewitnesses.
Therefore, this historian, who has presumably spent his entire life researching Roman history, has many documents that are independently verified.