"At least I went"
Now the visit itself, because penance changes what a visit is.
Picture two versions of Sunday. In the first you go because you should, with the clock on the cooker in view from the start and a running calculation about when you can leave. You do the jobs. You're pleasant. You're also, in a way your mother can feel and can't name, not quite there. In the second you go for an hour, an hour you chose, with nothing after it that you're pretending isn't there, and you sit down and she tells you the thing about the neighbour and you listen. Same house, same mother. Different visit.
I can't cite you a study on which one she'd prefer, and I won't pretend to. But I'd ask you to notice which one you'd prefer if it were you in the chair. Nobody wants to be visited as penance. Being someone's obligation is an unpleasant thing to be, and the elderly are not bad at reading it. What the penance visit gives the parent is a body in the room and the jobs done. What it takes is the thing they were actually waiting for, which was you, present, for a while.
There's a knock-on. The penance visit doesn't cancel the guilt. You'd think it would, since that was its purpose, but the guilt on the drive home is as strong as the guilt on the drive over, because you know, at some level, that you weren't really there. So the visit gets logged as done and not as good, and the should starts again by Wednesday. Penance is like that. It's paid in a currency the debt doesn't accept.
The chosen visit, the one given whole, does something the penance visit can't. It ends. You leave, and it's finished, and the next one is a separate thing. Chapter 20 is about how to make more of your visits that kind. For now, the point is only that "at least I went" is the sentence of a visit that was made to be logged, and both of you know it.