I agree that checking pressures with gages should not be part of routine maintenance. There are several methods to verify that the charge is adequate.
Keep It Sealed
After initial installation and system commissioning, there is no reason to install gauges. It runs the risk of creating leaks, losing refrigerant from installing and removing hoses, or otherwise accessing the sealed system and violating system integrity.
All information pertaining to the sealed system's performance can be accurately evaluated using temperatures alone with knowledge of design. A thorough understanding of system design and field practice of benchmarking systems will save time, increase equipment life, and reduce refrigerant emissions.
Checking The Charge Without Gauges | ACHR News