Well more so that the pick strokes line up so the lick can be cycled using the same directional picking pattern as before.
I would say decending is the trickiest for most people. If you are a wrist predominant player, and you are used to the subtleties of wrist playing, descending economy typically takes a little more broad forearm elbow movement on the turnaround of the lick, so you are kind of constantly changing between two fulcrum points.
Also, besides sweeping arpeggios, thereâs not a lot of times in typical guitar playing anyone really has to do many consecutive upstrokes, so it feels strange and uncoordinated, where as thereâs plenty of times you would use consecutive downstrokes (heavy palm muted chords etcâŚ) so as guitar players were used to them. Also gravity. You could let your hand go limp on the strings and it could fall do all down strokes, whereas you have to use more effort to lift your hand in order to do all ups.