Legato technique is essential, and contrary to popular belief, it is not necessarily “easier”
just because you don’t have to pick as many notes. The left hand actually has to work
harder to get all those hammer ons and pullofs going. This is especially true when transversing
from one string to the next.
The following example is in the key of E minor and it uses patterns of 6 notes spanning
across 2 strings. Try moving the same pattern to various sets of strings or transposing
it to different keys.
https://www.virtuosoguitarsecrets.com/content/2stringlegato.php