I have had three and currently own two.
One is right on time and has been running smoothly for about 5 years. You set it and tweak it daily for about a week then ignore for years ... hopefully.
The other one is currently not running, and never has run well in my 10 years of ownership. It’s been back twice for a service, new spring and a few other things. I even tried keeping them side by side ala Resonance but that didn’t work either.
I have my good one on a marble-topped table. They must be absolutely rock solid stable — I think a bolted-on wall shelf is best. Not near fireplace, open window or children.
Your experience may vary!
Cazalea