I absolutely regret that the whole idea of deep learning in Tosphot is almost forgotten. But it is nothing that I can do on my own.  It takes a sort of talent plus IQ to be able to see the depths of the Tosphot. I could see this in Shar Yashuv, but I certainly was no where near getting to that myself. And later I saw this again when I was learning with David Bronson.

But it has nothing to do with the so called ''pin test.''  Most people that imagine that they understand Tosphot have no idea of what Tosphot is saying.  Part of the reason is that learning in depth largely means learning Reb Haim of Brisk and the general achronim that came after him up until Rav Shach. And that kind of "global learning" is great. That means getting into the depth of the Gemara as compared with the Rambam which often apparently disagree, but with great ingenuity the achronim often find a way to show that the Rambam is not really disagreeing with the Gemara, but understanding it in an uncommon way. This is worthy and great in itself, but one unexpected result is it leaves  people not knowing the depths of Tosphot,

I spent a lot of time learning  the achronim before Reb Chaim and that was helpful because they do look into Tosphot. But the learning of the Maharsha and Pnei Yehoshua is uncommon. and even then it is rarely understood.