Should I be moving elbow when picking different strings?

Whenever I play songs/melodies where I have to pick along multiple strings, I have been only moving the angle of my wrist while keeping my elbow at the same spot when moving to another string, but I recently saw a video where it was instructing to push your elbow in when going down the strings and then pull it up when going up the strings, while keeping wrist movement minimal. I've tried to search online to see if this is a good idea and should spend time focusing on it or if it doesn't really matter. If it makes a difference I mainly play acoustic guitar. Should this be something I put a lot of effort into learning or something completely unnecessary? 

If it is something I should learn does this also apply to strumming or mainly just picking?

You can try moving the elbow up and down and see how it feels to you. I do what feels good for me, if the way you're doing it feels good to you, then do it that way, there are no set rules. If it feels good and sounds good, I wouldn't worry about it.

Ah okay then. I'll try doing it for a couple days and then see how it works for me then.

In general you should aim for the most relaxed & natural position for efficiency of motion.  That might slightly change depending on the musical context (exactly what notes you are playing on what sets of strings).  With strumming this usually results in a slight elbow motion with additional wrist motion to change pick angle to graze lightly over the strings in either direction.

With picking this usually results in more small scale finger & wrist motion with the forearm braced against the guitar body therefore little elbow motion.

I cover the basics of picking & strumming technique here.

https://www.guitartricks.com/lesson/10658

Hope that helps!

The video you saw with the instruction to push your elbow in when going down the strings and pull it up when going up sounds intriguing. Trying out new approaches can be a fantastic way to improve your skills.

As for whether you should put a lot of effort into learning this technique, it ultimately depends on your personal preference and goals as a guitarist. Experimenting with different techniques can help you find what works best for you and makes playing more enjoyable.

Since you mainly play acoustic guitar, it's worth noting that different techniques may have varying impacts on your sound and overall playing style. So, it's definitely worth exploring and spending some time practicing this technique to see if it suits your playing style and enhances your sound.

Regarding strumming, the elbow movement technique could apply to some extent, especially if you're doing intricate strumming patterns that involve quick changes between strings. However, strumming typically involves a mix of wrist, forearm, and elbow movements, depending on the pattern and the sound you want to achieve.

Remember, there's no right or wrong way to play the guitar – it's all about finding what feels comfortable and helps you produce the sound you desire. So, don't be afraid to experiment and see how this technique fits into your playing routine.

Keep up the enthusiasm and dedication to improving your guitar skills. Every new technique you learn adds a little more depth and versatility to your playing.