When my grandmother gave me her piano when I was in 4th grade, she included many things with it. Sheet music, a lamp, even a padded cushion for the bench! But the most important thing that she passed on with the piano to me was her metronome. She had played piano and cello for much of her life, and I know that metronome gave her much assistance in playing music.
But as for me, I learned to HATE that metronome. Do you know why I hated it? Because I either played faster or slower than the speed of the metronome. So, it quickly became an annoying reminder of the fact that I was off. It aggravated and frustrated me. But now, as a more mature and well seasoned musician, I know better.
I will still use that metronome (or the app on my phone) for difficult passages that I’m trying to work out. But, the most important thing for me is that I start slower than the finished product will be. Why? Because if I can get it down and confident at a slower speed, as I slowly increase the speed, it will become easier.
I encourage my students to use a metronome, not because I want them to be ahead or behind the beat. I want them to be on the beat. It is possible to do, and when you effectively use the metronome at a slower speed, then you will find yourself being more competent and steadier in your tempo without having to use it!