Effective practicing is thinking like a scientist.
You create a hypothesis. You test it. It may or may not work. And then, you move on to the next hypothesis.
If I schedule my practice time for every day at the beginning of the week, then I'll practice every day.
A week later, you only practiced two out of seven days. Hypothesis failed.
You could then move on to something like...
If I tell five of my closest friends I'm practicing piano every day, then I will practice every day.
A week later, you've practiced every day and you're excited to tell your friends. Hypothesis successful.
Or, in a practice session itself.
If I practice these first 8 measures slowly three times, then I will be able to speed it up a little bit successfully.
Clear metrics. Easy to judge success or failure. Move on to the next one.
Rinse and repeat.
Do it enough times for days, weeks, months, and years...and before you know it, you'll be called an "overnight success."