We are commanded in the Torah to say birkat hamazon (though the obligation from the Torah requires one level of satiety while the derobonon obligation is different). This obligation is derived from Dev 8:10 which reads וְאָכַלְתָּ֖ וְשָׂבָ֑עְתָּ וּבֵֽרַכְתָּ֙ (though in context, I wonder if the obligation should only be incumbent on people living in Israel).
But Dev 11:15 only reads, " וְאָכַלְתָּ֖ וְשָׂבָֽעְתָּ" as does Dev 6:11. Dev 8:12 also reads, "פֶּן־תֹּאכַ֖ל וְשָׂבָ֑עְתָּ" so the majority of times when eating to satiety appears, there is no requirement to make a bracha!
Why would there not be a commandment 3 of the 4 times when the behavior is discussed (even before the mitzvah is written down)? Is there significance to the fact that 75% of the time that that behavior is described, there is no commandment to bless?
I understand that there is an explicit commandment to bless but I might think that the fact that there are also explicit statements which choose not to demand blessing might present its own significance.