ALL DAY / EVERY DAY

After trying hard for years -ten years- to make a person bilingual, suddenly I hear her say to my face: "This afternoon I will be busy, as all Sundays..." (como todos los domingos.)
To confuse, at this stage of the game, all Sunday with every Sunday is very disheartening to say the least.
This simply means that Spanish has gotten the upper hand, finally. And English will not be the other language, but the second language, the poor relative.
It is a sad day. A day I never thought would come, after ten years.

I work all day, trabajo todo el día.
I work every day, trabajo todos los días.

I studied all day, estudiaba todo el día.
I studied every day, estudiaba todos los días.

I will visit my uncle at the hospital all day, visitaré a mi tío en el hospital todo el día.
I will visit my uncle at the hospital every day, visitaré a mi tío en el hospital todos los días.

¿Tan difícil es esto? ¿Es esta cuestión sólo al alcance de mentes privilegiadas?