Confessing once a year

[VeryTas]

Canon 989 says: "After having attained the age of discretion, each of the faithful is bound by an obligation faithfully to confess serious sins at least once a year."
I believe I looked up the similar Canon in the 1917 Code and it did not distinguish the obligation as having to do with serious, grave, mortal, or any other adjective, just sins. So my first question is, when and how did it come to be understood (before the current Code of 1983) that the obligation did only apply for serious sins? For, we find the Baltimore Catechism identifying the sins in question as mortal, even in my 1945 copy. I searched canonical archives and tweaks by any intervening Popes in vain.

It may or may not be related, but I have a second question. When and how did the practice (in the U.S. in the 1940s-50s) originate of telling those laity who would be receiving communion that they must all confess ahead of that Mass?

[Obi-Wan Kenobi]

It’s quite possible that the first change was made in 1983.

I have no information on the second question. I have no idea how widespread this practice was.

[anawim]

It may or may not be related, but I have a second question. When and how did the practice (in the U.S. in the 1940s-50s) originate of telling those laity who would be receiving communion that they must all confess ahead of that Mass?

We were told that we had to confess every time we committed a mortal sin. That was coming from Pre-Vat II nuns, so they made everyone think that everything was mortal, even if it might not be. They struck the fear of God in us.

[Obi-Wan Kenobi]

One should still confess before receiving if you're aware of an unconfessed mortal sin.

[peregrinator]

The thing about the yearly confession is not that there's a recommendation to confess only once per year; it's the bare minimum and since it's a precept of the Church, you commit objective mortal sin by not fulfilling it.

[Obi-Wan Kenobi]

I can't imagine waiting a year to confess a mortal sin!