Scale Shredding Technique (detailed question)

you may have heard it many times but its the truth,
you are the only one who can figur out how to do it,
do it any way you feel it right, personally when the 3rd finger hits down i move the 1st on the next string,
the only (and its the best) advice you can have is to play with metronome always and play SLOW!!! too damn slow,
forget speed, try practise at 52 its the only way you will get focused and you will get rid of all the bad habits that dont allow you to play faster,
Remember practising doesnt mean playing as fast as you can,
practise is when you realize what you do wrong and correct it,
the only reason you dont play faster is because while you play you make mistakes, and to correct the mistakes you must play SLOWLY!!!!

Blues Shredder

I've been through that phase of relentlessly practicing monotonous alternate picking staccato exercises. At the lower frets (1-7), I think it is better to keep your fingers perpendicular to the fretboard since the frets on this part are far apart from each other. It is also easier to play clean legato with the fingers perpendicular to the fret-board. But as you go to the higher frets, it is easier( for me) when the fingers are slanted toward the body. To do this the thumb would naturally curl around the neck for a better grip.