I see many legato practices didn't mention about it.
Each time i play 3 notes in one string, i tend to lift all 3 fingers and pick the next string first note (2 left fingers are on the air).
I notice that this way make the previous notes lose their sustain, then i try to keep these two fingers on the first string until i pick the first note on second string then use hammer on on the rest (like spider walk practice)
It sounds more smooth, but i'm not sure is this the good practice for legato since it slows the movement down?
Edit: To have more clarity, i play 3 notes on the low E string, then ascending 3 fingers on the A string. Pick the first note, two remains on the E string while the first move to the A string and pick (this is spider walk and sounds smooth to me.
If i lift all fingers from the E string before picking the first note on A string, it sounds not smooth (not spider walk)
Here are the photos of the moment changing string from E to A: