In an attempt to clarify matters:
From Jan/Feb of 1920 when "Golf Architecture" is first published in London (number of copies unknown at present) until January 29th 1926, when MacKenzie arrives in San Francisco, there's not one recorded meeting between MacKenzie and any of the "California" architects in his diary/timeline. In addition, there's no record of any correspondence, in letter form or telegraph, between MacKenzie and any of the California architects.
In addition, Mackenzie did NOT move to America in 1926.
He visited California briefly in 1926, for about a month,
from Jan 29, 1926 to late February and departs NYC for the UK on March 2, 1926.
It's unclear to me if it was his brother Charles or Alister who visits in July/August.
He's in the UK in August, 1926 and sails for Australia on Sept 19, 1926.
He remains in Australia/NZ for months and arrives back in San Fran on Feb 18, 1927,
where he spends less than a month, going to Philadelphia in Mid-March
and then departing NYC for Southampton on March 26, 1927.
He returns to NYC on Jan 20, 1928
Arrives in California on Jan 29, 1928
Less than a month later he sails from NYC to Southampton on March 17, 1928
August 18, 1928 CPC opens and MacKenzie is not there.
On August 18, 1928 Mackenzie sails from Southampton to Quebec, Arriving on August 26, 1928
He's in California in early October, and goes to Chicago around Oct 16-20, 1928
And then sails from NYC to Southampton on Oct 24,1928, arriving on Oct 31, 1928.
On Jan 28, 1929 he arrives from Southampton, and is at Pasatiempo on Feb 4, 1929.
He's back in the UK attending the Ryder Cup at Moortown in April 26-27, 1929
He arrives back in NYC on July 26, 1929.
In California August 3-13, then back east On Sept 30, 1929
In Chicago Dec 2, 1929.
On Jan 24, 1930 he sails from NJ to Argentina, arriving on Feb 10-12, 1930
April 9, 1930 he sails back to Southampton, arriving April 27, 1930.
Gets married to Hilda a few days later in London on May 9, 1930.
He sails from Southampton on June 7 and arrives in NYC on June 13, 1930
He's in California in late June/early July and moves in to his California residence in Santa Cruz in November 1930.
He did not come to reside in America until four (4) years later in 1930.
So, the notion that MacKenzie was in residence in the U.S begining in 1926 is false.
And, he certainly didn't spend the bulk of his time in California from 1926 to 1930.
On his Feb, 1926 visit to California it's recorded that he and Hunter spent time visiting courses in the Bay area, thus dismissing Sven's claim that there weren't many courses in California at the time. When he visits Los Angeles he does the same thing, visiting Riviera and Merwick. So we know that courses such as Riviera, Merwick, Ojai, Palos Verdes, Red Hill and other were already being played and that a good number of other courses were already under construction or built, awaiting grassing by the time of his visit.