So I've always wondered whether there is some agreed method of how to efficiently pick scales moving from string to string, or if it's all a matter of preference.
When ascending for example a simple Am pentatonic would you (assuming I'm moving down the strings from 6th to 1st):

DU, DU, DU, DU, DU, DU; or instead: UD, UD, UD, UD, UD, UD (I feel this movement could be more economical in the sense that on the down stroke your hand is moving in the direction of the string below it, but I know this can also affect the sound by means of your attack, correct?).
Refering to the previous scale would a decending pattern just be(going from the 1st string to 6th):

UD, UD, UD, UD, UD, UD? or DU, DU, DU, DU, DU, DU?

& When ascending three note per string scales, for example a G Maj, would one:

DUD, DUD, DUD, DUD, DUD, DUD; or DUD, UDU, DUD, UDU, DUD, UDU (is the first pattern just economy picking and the second alt.? )

These might be no brainers, but I'm really trying to get a set method of practicing my picking movement down and some clarity in this area would help immensely.

Go with whatever's easiest, but economy picking will always be quicker than alternate picking for a given picking speed.

__________________

That's what I figured, thanks for the advice.