Alternate Picking

I'd say that for practicing purposes you should always do strickt alternate picking until it's become really second nature. In a given playing situation the answer is that it depends - on whether or not you change string, on the rhythm etc. Impossible to answer universally from the examples you give.

..but then again I am never going to be a speed monster.

I teach picking through a fairly logical progression: downstrokes, alternate picking, economy picking, and other techniques (sweeps, taps, etc) last. How a particular piece should be played depends on a bunch of things... the rhythm (whether the notes fall on or off the beat), which strings the notes are on, and the tempo of the piece. The "best" picking pattern is going to minimize pick motion while keeping a logical relationship to the beat, and one strategy won't work in all situations.

Alternate picking is generally efficient, but it depends on the rhythm. In general you want downstrokes to fall on the beat, and you want your hand to follow a logical pattern related to the beat. For example, four sixteenth notes would be down-up-down-up, but a rhythmic figure of an eighth note followed by two sixteenths should be down-down-up, and a sixteenth-eighth-sixteenth would be down-up-up. That way your hand is making a steady motion - you're moving up for the "missing" sixteenth note (the second half of the eighth note), so your picking hand is helping you keep time.

But let's say you have a set of four sixteenth notes that lie on strings 1, 4, 2, and 3. Then the "best" motion is reverse alternate picking, which puts an upstroke on the beat. You do that to be efficient - your hand is always moving in the direction of the next note you're going to play.

Another figure might put successive sixteenth notes on strings 3, 2, 2, and 1. Now we're getting more complicated, and tempo can be a deciding factor. At a slow speed, I'd probably play it with alternate picking, because it's actually harder to play in time at slow speeds than fast ones, and I'd want my hand to help keep time. At faster tempos I'd use "economy" picking (which some teachers call "directional" picking) and play DDUD or DUDD - either one combines two successive strings, moving in the same direction, into a single pick stroke. (Practice tip: develop the habit of making the pick come to rest on the next string as you play - that will give you more control over timing and dynamics than trying to make your hand hesitate in mid-air). And if that same figure was played at a very fast tempo - say 200bpm - I'd sweep it in a single downstroke, playing the third note with a hammer-on or pull-off.

Other factors can also play a part in figuring out the "best" way to pick a phrase. In general you'll have better control over accented notes when they're played with downstrokes. And in general, a complicated division like quintuplets or septuplets (five or seven notes in a single beat) are easiest when you can combine two or more notes in economy/sweep picking.

But whatever pattern you choose for a particular phrase in a piece, make sure you always practice it using the same strategy. Consistently good timing depends on consistent picking.

Thanks Noteboat, much appreciated.