I've been mainly sticking to practicing this scale for a week or two now. For my whole life, whenever I sat at a piano, I would do a C major scale. I didn't know any others. I personally think that the C scale and key is a piano prison. Any advice I would give to beginners is that yes, by all means, have a go at the C major scale, but DON'T stick with it for too long. I would go straight to a key/scale that has at least two sharps in it. D or A major because they really give you a sense of what practicing in a different key is all about. In fact learning other keys is like learning a whole new instrument.
Anyway, I started the scale at a really low bpm (anything from 60-100 bpm). Abrsm syllabus guidelines are quavers, so when you see the speeds for whatever grade you are going for, you need to do two notes per beat. So when I say 60-100bpm, it means 30-50 bpm with two notes per beats. I just prefer hearing the metronome beat on every pulse so I just double the speed.
Something quite strange happened when I was doing the scale....
After going up in increments of 5 bpm after a couple of two octave repetitions, I found that I would try to remember to relax. The more I relaxed, the easier it got. It's like time was slowing down. My fingers were kept really loose, almost jelly like. No tenseness or even 'pressing' of any kind. I felt like I had more time to concentrate on the small movements to do the thumb under transitions. I would describe as quite zen like. At around 140-150 bpm, I found myself able to watch my fingers and not have to think at all about trying to go fast. It was a revelatory experience that I only imagine virtuosos have found out about. From then as I increased the speed I started to find it harder and found my fingers tensing up to be able to keep up at that tempo. I did reach 180-190 but it was not even at all and had frequent stops and mis-hits. After getting tired, I realised it had been about 30 minutes and that was enough and I had already achieved quite a bit. I noted down the speed and scale in spreadsheet with that date and any comments about the session. Then played two of the grade 1 exam pieces (Mozart and Turk). Damn mozart still having trouble with fingering. Turk is going really well. Have it pretty well memorised and up to a nifty speed accurately. I even tried some slurs which are mentioned in the teaching notes as giving extra marks in the exam.
More to look forward to for my next session now. Will aim to get back in the zen mode and try and push that 150+ bmp accuracy.