Knowledge once thoroughly absorbed is often retained. But rarely perfectly, and in the cases of a lot of activities, it takes a great deal of relearning to come back up to speed.

Case in point, a lot of time is wasted at the beginning of the year in schools here in the US having to reteach what kids have forgotten over their extended summer vacations. Which is one of the reasons there are a lot of people who advocate for year-round schooling.

If you're convinced that Martha somehow magically remembered everything she learned in school despite being away from it for so long, there's not going to be anything I can say to dissuade you. I'll be interested to see if/how they handle it in TW and DW next year.