A lot of intermediate guitarists get to the point where they don't know what to do in order to take their technique to next level. The biggest problem they encounter is not just the time and discipline to practise but more often than not how to. Some people get into the mindset that you have to spend hours a day practising and think they have to practise chromatic runs all over the freeboard and quickly get bored with what they are doing. They just do endless amounts of exercises built to develop technique but their does come a time where you need to leave most of this behind and focus on licks and phrases that you want in you playing and learning how to apply them in different ways.
This is the method I use which I find is great and quiet simple. You collect a handful of licks roughly 5 10 and work on them for small amounts each day 5-10 minutes each depending on time, player and goals. These licks should cover all the techniques you want to develop these being sweep picking, alternate picking, string skipping, legato and tapping. You can also do economy which I have recently made a big part of my playing but I will keep this simple for now maybe I will do a lesson later about combing alternate and economy for the best of both worlds. You can choose to directly isolate each technique or you can combine various techniques for each etude, when you combine techniques in each run you will create more interesting runs.
To start with practise slowly with a metronome and get yourself to a rather quick speed. Then play it in different keys and different areas of the fret board. When this step is complete you can try the lick in various groupings say if the lick is in triplets adjust it to use it to quadruplets etc. This last step isn't necessary but for serious guitarist I recommend it because you can get totally different sounds with different groupings and it's also good for developing musically as a player.
The reason I work the one lick over in so many ways is because you really want to ingrain it in your head and make it a part of your playing remember its useless unless you can put it to use. Now obviously if you are practising an etude that already has a combo of different groupings and spans the whole fret board you won't be able to do the last step but for general licks I find this is a very important approach.
Also doing smaller scale fragments free pace is a great way to develop speed. Practise them in burst and this will help you achieve maximum speed. This approach is also good for practising difficult parts of licks that you can't nail and bringing them up to par with the rest of the lick.
So how much time do I need to practise technique a day? Well that's like saying how much food do I need to eat each day. The answer is it depends on your goals and how productive your practise sessions are. If you want to be a neoclassical metal guitarist you're obviously going to have a different amount of time to let's say a blues guitarist. Some people don't time themselves as well rather record the beats per minute and try and top it each day others don't have any specific system but this usually isn't a good approach, but can work for some because there is no right or wrong way.
You may have noticed that I haven't spoon fed you any licks and etudes but they are easy to come buy you can find them in songs and make your own also there's an abundance of great informational products out there.
Well that's it, and feel free to ask any questions and keep practising, cheers.