to do those pics fluently and without interruption when changing the strings i personally use economy picking (works with all uneven groupings of notes per string like 1, 3, 5, 7, 9, etc)

when picking 3 notes you simply start with a downstroke, then an up and a down again - so the motion after the last note is down - and now you do not alter the movement but sweep the first note of the niext higher string with the same motion as the last on the lower string. comprende?

like:

__d_u_d_d_u_d_d_u_d
e_____________1_3_4_
b_______1_3_4_______
g_1_3_4_____________

d=down
u=up