When you sweep up the neck and get to the highest string (or lowest to the ground, or thinnest....etc), do you hammer on your notes if the option is given? Or do you pick them?

Ex in E std on the highest string only AFTER you've just swept up EADGB... (I'm doing one line to save time)
 E | ----- 9--12--9---------|

Would you hammer on the 12th?

Reason I ask:
When practicing, should one be picking it to get the technique down properly? What about hammering on? Is there any useful time for this? What about if I wanted to tap something like

9 -- 12 -- 15 -- 12 -- 9

Would just practicing with picking hinder me?
Should I be training each individually? Like do 60 - 200 bpm workouts for a fortnight with hammer on's, and then another fortnight with no hammer ons?
For speed you can hammer and pull off the 12th fret on the first example. In fact I think its recommended that you do as in can mess up the picking motion.

I don't know too much about the second part of the question.
I always do legato on the last string. I find it sounds smoother anyway, helps the arpeggio "flow" better soundwise.
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