In feudal England, everything went to the heir-at-law by default.
The point of a will was to try to divert some stuff to other people, at the expense of the heir.
Anything not specifically bequeathed still went to the heir-at-law.
There was no point in making a bequest to the heir, because it would be coming out of his own inheritance.
In this case, John makes his will when his daughters are all still unmarried. Possibly none of his children is of age yet. They all get a bequest, including Robert, because everything else is being explicitly left not to the heir but to the widow.
But this only covers cash and chattels. No property is mentioned. Since there's livestock, there's obviously an interest in property, which will descend to the heir (Robert) unless otherwise entailed.
When Edith dies, Robert is again the heir, but much older now. There's no mention of property, but a widow's dower rights end on her death.
My guess would be that Robert has taken over his father's farm, probably when he got married, the year after his father's death. Edith gave him whatever household goods and livestock he needed, and is now living in a second house, as her widow's thirds, which has been settled on David on her death.
So she leaves the younger kids some selected bits and pieces they can use, then says everything else in the house goes to David, ie. it just stays with the house (where David is living). There's no need to leave any pots or bedding to Robert at this point, he needs them least. She has no cash.
Purely a speculation. Other theories are available.