I usually spend an hour and a half doing 6 string, 3 string and 2 string arpeggios and the major scale from various 6th and 5th string roots.
I also double pick the A minor scale. After doing this for 3 or 4 years now I have the metronome on 230 to start and it goes from 230 to 180 to 140 to 120 to 128 back to 180 during the course of my routine.
Its a practice regimen that I know pays off in a big way. At first you have to experiment to get a starting point for your metronome. And keep it simple.
Whole notes, half notes, quarter notes, sixteenth notes. Tap your foot every beat, then on the one and three, then the two and four - take your time. Time is one of the hardest things to find practical exercises for. This is a so-called master class but its also an advertisement for the Berkley College of Music that issues degrees.
Professor Stump teaches that the C major scale was the exact same scale as the A minor scale only starting on a relative note the 6th (A vs. C). Joe also shows us how to practice the scale 3 notes to a string and at different tempos. Stick with it as Joe teaches a 'master class' and if you aren't up with some concepts then maybe you might find he is going a little too fast?
His 'simple math skills' need to be slowed down for novices or people who haven't yet developed their sense of counting time. If you aren't used to it you will perhaps scratch your head and wish he would be more considerate. This is when you are glad you have a scale book to look at at your own pace! You bought a scale book right?
Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible.
Francis of Assisi