MoveTrainer in chessable is very good, I agree.
One of the strong player I talked while ago, told me to try to reproduce chess line/variation/sequence from memory, on physical board. I know it's more time consuming than doing this in the app, on the screen. But there's something special in moving physical pieces, that can't be reproduced on the screen.
So I've had all of Gotham PGN courses & really not a good way to use them for months.....until.
I found Chessable. With a free account & move trainer these courses work beautifully. I suppose I'm wondering why did it take almost a year for me to find this? I've been asking seasoned players how to use these PGNs effectively for study. Chessable is still just "the woodpecker method" as a friend of mine would say. But a PGN reader doesn't test you in any way. At least Chessable takes you through all the variations move by move.
It makes me wonder if there is something even better? What do you use to make effective study with a professional PGN?