If speed picking does not work on a particular scale, arpeggio or line, then you should default to Alternate picking. As a jazz guitarist you should strive to improve your picking speed. However, your ideas should not be based on speed alone but on more important concepts like composition, melody and rhythm. Songs become standards when they have a memorable melody and an interesting harmonic structure for improvisation. For example A to B, C to D are steps.
Steps are the building blocks of scales and therefore are important in their discussion.
A technique where the right hand plays the notes of a chord simultaneously either with down or up strokes. Go here and here for more Substitution is a mainstay in jazz. Virtually all jazz artists use substitution but a few artists, like the great chord melody player Lenny Breau and pianist Bill Evans, breathed new life into jazz standards with their remarkable and clever use of substitution. Jazzers strive to make a tune swing whether it is a ballad or up tempo. Listen to players like Wes Montgomery, Charlie Christian and Herb Ellis for classic, sweet and swinging eighth note solos.