Doing spider warmup drills issue

Should I assume that its optimal to never have any finger touch another string even when doing warm up drills?

I find it extremely difficult (read impossible) for my pinky finger to not touch the string below it, especially on the D, A & E strings. 

This is only the case when my other fingers are in there respected fret position also pressing down on the string. 

As you can imagine, the fingers are very spread out at this point, especially on the A & E strings. 

Is this something I should spend time correcting, or is it expected and move on? 

Thank you!

In a perfect world, we could all fret the low E string with index on the first fret, middle on the second, ring on the third and pinky on the fourth, without any buzzes or touching of adjacent strings. In reality, this can be hard to do.

With guitar, there's perfect form, and there's what you need to do to make the music happen. It technically doesn't matter if your pinky is touching an adjacent string, if you're not playing that string at that moment. And you'd never really need to have frets 1-3 fretted with your other fingers during a song, in addition to having the pinky on fret 4. So you could remove your other fingers and only have the pinky down, or maybe just remove the index and middle.

I would suggest the following:

*Try this exercise on higher frets, like frets 7 or 8, where the frets are closer together, making the stretch less.

*Try to put the pinky down cleanly without touching another string, while lifting up some of your other fingers if you need to.

Eventually this will get easier. The pinky is the most difficult of fingers, because it shares a tendon with your ring finger. Teaching it to be strong and have a life of its own can be hard. Don't give up on it.

No.  In fact it's often quite beneficial to have some part of your fingers touching adjacent strings in order to mute extraneous sounds.  I cover this in this tutorial on muting.

https://www.guitartricks.com/tutorial/2281/

Sometimes of course it's necessary to let an adjacent string ring open or sound another note.  You can work on those individual cases when they show up in the music you are playing.  But it's more often the case that you want to mute at least a little.

Another point about spreading out your fingers.  It's not necessary in every case & not even optimal in many cases.   When you are doing spider fingers it can help to maintain contact with the strings with the tips of you fingers, but release pressure and slide them up to make it easier to fret the next note & finger up the string.  You also slide you hand up the neck a little bit as you do this.   

This is great practice for three important reasons:  you are learning to move you hand up & down the neck shifting positions, you are learning to use minimal pressure & tension to play notes, you are learning efficient motion.

In some cases it is helpful to hold down lower frets (for trills & licks that require it).  But quite often it's better to just move your hand a little.

Hope this helps.

No.  In fact it's often quite beneficial to have some part of your fingers touching adjacent strings in order to mute extraneous sounds.  I cover this in this tutorial on muting.

https://www.guitartricks.com/tutorial/2281/

Sometimes of course it's necessary to let an adjacent string ring open or sound another note.  You can work on those individual cases when they show up in the music you are playing.  But it's more often the case that you want to mute at least a little.

Another point about spreading out your fingers.  It's not necessary in every case & not even optimal in many cases.   When you are doing spider fingers it can help to maintain contact with the strings with the tips of you fingers, but release pressure and slide them up to make it easier to fret the next note & finger up the string.  You also slide you hand up the neck a little bit as you do this.   

This is great practice for three important reasons:  you are learning to move you hand up & down the neck shifting positions, you are learning to use minimal pressure & tension to play notes, you are learning efficient motion.

In some cases it is helpful to hold down lower frets (for trills & licks that require it).  But quite often it's better to just move your hand a little.

Hope this helps.