The theory is that by making several sugar additions mid-fermentation instead of front-loading all of the sugar is that it will not shock/stress the yeast outright in the beginning by the high amount of sugar, and will allow the yeast to re-produce in a more hospitable environment, since alcohol (in high amounts) is toxic to yeast. With that in mind, you also don't want to skimp on the must though and do too low of a gravity, as the must will contain nutrients (albeit low amounts in comparison to wort in beer). I cannot speak to the positive/negative effects of this in fruit wine through experience, but I have done this with high-gravity ales to great success.
The only critique I can provide in your steps is (assuming a 5-batch) to dissolve 0.5 - 1 teaspoon of yeast nutrient along with your sugar addition before adding, depending on the size of the sugar addition. Staggered nutrient additions provide a nutrient-deficient fruit must with the proper nutrients needed to aid in a clean/quick fermentation and maturation. You can make these additions once the high krausen begins to die down so that you aren't concerned with blow-off or making a mess.