It's a long time since I was learning the piano, so I have no wise words about scales (that and they bring me out in hives, I cannot learn them at all! To the extent that I shifted to Trinity and did a scales-free exam after a scales fiasco with ABRSM... )
however, I did do preparing for exams whilst working part-time and raising a couple of kids, so do have this little nugget for you:
yes, it's good to set aside time to practise when you can, but we all have times in busy lives when that's either difficult or energy seems to have run out. There is something my kids' piano teacher called "patch practice", which is done in odd little corners of time, and it's surprisingly effective. If learning a piece, mark stumbling points - I do so with pencil brackets, either side of the problem section - and focus on those. It involves just playing those bits, slowly at first, maybe up to three times, and then getting back to whatever is actually needing to be done in the rest of life, and the beauty of it is, you can do that several times a day, just when passing the instrument. I'd do that when waiting for the kettle to boil or the rice to cook, for instance. You can work on a single difficult fingering transition for instance - just the thumb-under bit of an arpeggio maybe, or a section of your piano music where the notes take a turn for the unexpected and catch you out. When you're just setting out to learn scales, there'll be bits of the scales which sound smooth, others which have lumpy hesitations in them, and they're the bits which need ironing out - the smooth bits are fine already . Using that method, not for all my practice, of course, but when times and energy were difficult, I found I could get past some frustratingly tricky patches of music and still keep momentum and progress going.
The other thing to say is that the ceiling does move upwards - one level achieved and it feels as if there is still so much to learn, but the weird thing is that you can learn it. Sure, it's a slow process, it takes time to train muscles and brain up, but each little notch of achievement sets down useful footholds for the next one on the list.