These components all exhibit slightly different characteristics, so potentiometers are used to tune offsets and gains. Sometimes, lots of pots are used. Without this equipment these adjustments simply cannot be made in the field. In most cases a bit of clever software can take advantage of a panel display to replace the test gear. Write a bit of code to show raw voltage, or whatever is being monitored, on the system's own output device.
Pots are a continuous source of frustration to users.
Try writing code that removes offset, gain, and other errors mathematically. When you design diagnostics for field or in-house use, be sure to bear in mind the sorts of tools users will have available. One of the most useful troubleshooting tools is the venerable oscilloscope. Most test and repair technicians rely on the scope almost exclusively. Logic analyzers, emulators, and the other tools used in engineering are not nearly so ubiquitous in the test environment.