And if so, would that mean anything? One question at a time.
According to Zuckerman & Blosser, the year AD 26/27 was a Jewish year of rest. (According to Wacholder, it was 27/28.) But we also have competing dates on John's ministry. If the two year chronology of Jesus' ministry were correct, then John's public phase began at some point in AD 27, likely overlapping with the year of rest (whether early or late that year). If Hoehner's three year chronology were best, then John's preaching began in AD 29, farther out of this question. And if Cheney's four year chronology is correct, John started preaching in AD 28, early enough to intersect with Wacholder's year, but a handful of months after the end of Zuckerman & Blosser's.
First point: it's worth considering some possible connections here.
In one scenario, assuming anyone still observed Moses' law on these things, it might have raised John's profile to deliberately coordinate his public splash with a Year 7. Furthermore, if some agricultural workers had time off, his crowds might have grown somewhat, and though most farmers seem to have ignored the Sabbatical by this era, it may have been precisely such people - the sacrifically observant, the 'radically orthodox', the 'Essene like' among Israel - whom John most wanted to draw.
In a different scenario, John - or perhaps, rather God - waited until just after the Year of Rest to begin this new work. This theological supposition may not be historically scrutable, but it would fit the chronology beautifully. In fact, with Cheney's chronology and Zuckerman's years, the ministries of Jesus and John - together - would fill up the six year period in between Sabbath Years, with some spare months left over at either end. A six year run for the first man of a new race, in the sixth of six Sabbath-Weeks during Jesus' 38 years on the Earth... *Ahem* (???)
I repeat: Numerology and Theology do NOT serve as historical evidence. For completely separate reasons, however, I happen to prefer scenario two.
But none of this is my point. This is:
These are merely examples of questions, both theological and historical, of the kind that simply cannot be asked until after chronological work has been done. So, the fact that most New Testament Chronology work tends to stop asking questions - usually at whatever point it 'concludes' for some dates over others - says something about what NT Chronology may have been all about, in the past. And maybe that was just fine, for the past.
Moving forward, NT scholars who work with Chronology should attempt to do much more than assign dates. In my humble opinion, chronological investigation has no point - no purpose whatsoever - unless it's the launch pad for doing actual History... and yes, maybe even Theology.