I think around M15 is the threshold for the average (decently skilled) Tetris player. My record is M17, but I start creating more garbage than I clear them up at M15, so pretty much the same.
Yeah but trying to beat Shirase under the Classic Rule restrictions is another story. That being said, i acknowledge TE Master being harder than World Rule Shirase
1 frame may not seem like a lot, but keep in mind that when it reaches values that low, 1 frame is 16% of your lock delay at M29, and 20% of it at M30.
Here's an explanation if you don't know what I'm about to say. Where is M Ultimate(MU)? M Ultimate is basically M35, just renamed differently. The time to lock is probably 1 frame, which is impossible for a human being, but a boost is added so they can do MU. Whoever can beat that speed, will get an SSS rank, which is insane, but if you're able to get it, congrats! Now life has been accomplished so MOVE ON SOMETHING ELSE. Have a nice day.
I dont have tetris effect but from what i understand, the lock delay is only 5-6 frames, so theres a very small window to move the pieces, sometimes he just can't move it to a good spot in tiem