Chromatic's are a great way to get started, because they build up good syncopation, but what it means is that if you plan on playing four notes per string very fast, then it will work great, but if you don't want to restrict yourself, then you need to work on other things as well.
Let's say two notes per string, then four on the next, three on the next one, etc. Or maybe string skipping or pedal tone passages.
Even if you get really fast, you really have to break everything down, and account for everything. If you start thinking like this, you'll start to see all sorts of combinations of notes and strings that you can work with.
A lot of guitar players can play fast, but they can only play certain types of runs fast unfortunately. Try and think about how you can mix things up to improve your accuracy. Hope this helps
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