Progression of the sabino1 splashed white 1 combo feels a bit off. Given that both of the genes apply more white for homozygous horses than heterozygous, I'd expect the more the genes, the whiter the horse. However, that's not the case.

I haven't encountered any single 90%+ white SB1/SB1 horse that also has SW1 present. Homozygous (SB1/SB1) horses share patterns with heterozygous (SB1/n) when combined with at least one copy of SW1. SW1/SW1 seems to limit the area of white even more than SW1/n.

n/n SB1/n:

n/n SB1/SB1:

SW1/n SB1/n

SW1/n SB1/SB1

SW1/SW1 SB1/n

SW1/SW1 SB1/SB1

So unless it is intended for SW1 to apply some sort of reverse engineering on SB1 and itself, this progression isn't correct since SB1/SB1 alone results in nearly whole white horse.