Technique: A Possible Guide on How to practice.
First of all, it definitely seems like there is no such thing as a 'one size fits all,' some people go to practice for an hour a day and within a year, are picking in a way that makes Malmsteen jealous (maybe an exaggeration, but hey!). Others, will sit with their instrument for a whole day, achieving similar results.
Why is this? In my opinion, it is most likely to do with how well structured their practice time is and how present a person is practicing. Remember, we are talking about technique here, so in my mind that means performing music with efficiency, clarity, control and precision. Personally, I practice technique, on average, an hour a day. This is all I need to actually feel like I am making progress, without feeling like I am only singularly facetted in my guitar playing. This leaves me more time to work on composition, improvisation, singing, production, brand development etc, and to spend some time away from playing.
What do I try to do in these practice times? Simple, I will have a phrase that uses a specific mechanic of technique, i.e. string skipping/tapping/economy picking, and I will practice that. For example right now, I am practicing the crazy tapping line from Wonderful Slippery Thing by Guthrie Govan.
As for structuring my practice time, I group it into 25 min segments, with 5 minute breaks. I will try to play nearly as much as possible in that time, then, during the break, I will put my guitar down, get a drink... you get it.
During that time I make sure I play at a speed (with a metronome or recording on a loop) with a couple of errors. It feels uncomfortable, but not impossible. Then sit with it for a bit, get it right three times in a row and then speed it up by 5 bpm. Small increases lead to massive changes in a minimum amount of time! Aside from this I have found a killer metronome online that increases incrementally, after a set amount of time! Check it out: https://www.studybass.com/tools/online-metronome/
Without saying, during this time, I make myself present. So, no phone; no Netflix going on in the background. It's me, the guitar and a metronome.
I hope this helps!