More to biennial bearing than last year's crop load
I've been in many different orchards this last week and the flower set of various species is better than I've ever seen. If the sites had been frosted out last year this would be expected, but most sites weren't hurt by last seasons May in March, April in April weather.
I've long suspected that a longer season allows the trees to store more energy, which is responsible for better flower show the next season, but I'm not sure this makes any sense, because the tree starts forming next year flowers early in the season and all the literature talks about needing to thin fruit very early to assure good set the following year.
But it this was literally true there would be no tip bearers as those flowers have to be formed later in the season. I remember a lecture given by a commercial grower I attended years ago in which he had very clear evidence that late season flower formation is a very important factor in next year's crop, but, unfortunately, I've forgotten what his evidence was.
I rely a great deal on hand thinning performed much later than proscribed timing to assure annual crops but I begin to believe that even late thinning must be helpful- anything that increases energy in the trees bank account must be.