I stumbled across a practice technique years ago when I was teaching music.
When working scales or linear passages, we generally start slow and work our way up to whatever our target speed is....if we ever get there.
I had one of my professors pass this little trick on to me and it literally cut my scale drill time in half and was incredibly effective in working thru some very dense, linear passages in my recital repertoire. It is stark in it's simplicity.
I'll use a scale drill for example. When we're practicing scales, we're concentrating on an even passage and building speed and techinque.
Start your scale drill this way....swing the notes...that is, 1st note long, 2nd note short, 3rd long, 4th short, etc...alternating long and short durations. This yields a kinda lilting rhythm. Do it at a very comfortable tempo..don't try to push it. Concetrate on keeping it consistent and slow. When you are able to do this several times without any problems, switch the rhythms around. Start with the short note 1st, the long 2nd, short 3rd, etc...
It'll will feel awkward at first and it's hard as hell not to rush. Keep it slow. When you can do this several times without a mistake, then just play the scale in the regular manner, each note equal in duration.
The scale will feel ridiculously slow and you'll find you can play it quite a bit faster. When you want to kick the speed up again, repeat the rhythms again at a fast tempo.
This is also great for working thru linear solo passages. It will cut your practice time down considerably and help build your technique equally.