The method in one paragraph
Choose four bars. Loop them. Start slower than feels necessary, at 60 % or even 50 %. Play the four bars cleanly three times in a row, and then raise the speed by one step. If you slip, drop back one step. Stop when you reach the speed you want, or when the session is over.
Setting it up
Play the recording to the first bar and press Set A, play to the end of the fourth bar and press Set B, and the loop begins. Then set the Speed row. PitchShed does not raise the tempo for you: you press + yourself, in steps of 5 %, which keeps the decision with the player.
The three-in-a-row rule
Three clean passes in a row is a simple test. One clean pass can be luck, but three means your hands have it. Count out loud if you must. If you cannot get three, stay at that speed a little longer or go down a step; the slow speed is not wasted time.
Why four bars
Four bars is long enough to feel like music and short enough to repeat many times a minute. If the trouble is only one bar, loop just that bar and widen the loop again afterwards. Move the loop forward when the section is solid.
When to stop for the day
Stop a session while it is still going well, not after a run of mistakes. A short, clean final pass tells your hands that the passage is something they can do, which is the feeling to carry into tomorrow’s practice.
Keeping your place
Close the tab when you are done. The loop and the last speed are saved with the video; the next session opens with the same four bars at the speed you reached.