Has anyone built a precise Arduino-controlled robotic arm with potentiometer/servo control?

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Has anyone here built a multi-joint robotic arm using Arduino and servos (with potentiometers or direct PWM control) and achieved good repeatable accuracy? I was looking at a practical guide on controlling servos with Arduino that covers wiring, PWM and example code (https://www.theengineeringprojects.com/2017/05/servo-motor-control-using-arduino.html), and it looks like a solid starting point for a small arm.

I’ve also read Arduino Forum threads about servo jitter and power supply issues, and seen Instructables/CircuitDigest projects that use potentiometer master-arm control or record-and-play techniques. For those who’ve built one: what helped most with smoothness and repeatability, better servos, separate power rails, calibration routines, filtering, or something else?