Hit and miss coming from a salesman = we’ve had little fruit. In a great fruit set yr it doesn’t need thinning = the darn thing doesn’t set unless the stars align.
Before that he’s thinning by pruning. That’s a good idea. However in CA where it doesn’t freeze in spring he could have done better and much faster by winter pruning. We’ve had pics here lately of much better looking bloom and trees shaped by winter pruning. Look at blueberrythrills trees post 59 here: 2016 Peach Tree Pruning - #57 by tonyOmahaz5 Much better looking trees for CA.