  We present a long-term overview of the atmospheric phase stability at the
Atacama Large Millimeter/submillimeter Array (ALMA) site, using >5 years of
data, that acts as the successor to the studies summarized two decades ago by
Evans et al 2003. Importantly, we explore the atmospheric variations, the
`phase RMS', and associated metadata of over 17000 accrued ALMA observations
taken since Cycle 3 (2015) by using the Bandpass calibrator source scans. We
indicate the temporal phase RMS trends for average baseline lengths of 500,
1000, 5000, and 10000m, in contrast to the old stability studies that used a
single 300m baseline phase monitor system. At the ALMA site, on the Chajnantor
plateau, we report the diurnal variations and monthly changes in the phase RMS
on ALMA relevant baselines lengths, measured directly from data, and we
reaffirm such trends in atmospheric transmission (via Precipitable Water Vapour
- PWV). We confirm that day observations have respectively higher phase RMS and
PWV in contrast to night, while the monthly variations show Chilean winter
(June - August) providing the best, high-frequency and long-baseline observing
conditions - low (stable) phase RMS and low PWV. Yet, not all good phase
stability condition occur when the PWV is low. Measurements of the phase RMS as
a function of short timescales, 30 to 240s, that tie with typical target source
scan times, and as a function of baseline length indicate that phase variations
are smaller for short timescales and baselines and larger for longer timescales
and baselines. We illustrate that fast-switching phase-referencing techniques,
that allow short target scan times, could work well in reducing the phase RMS
to suitable levels specifically for high-frequencies (Band 8, 9 and 10),
long-baselines, and the two combined.
