  We present the results of a 5-year monitoring program of 42 sources targeted
at 6.7 GHz methanol masers, conducted from March 2017 to October 2022 using the
Irbene 32 and 16 meter radio telescopes. Sources were observed with irregular
intervals where time between two consecutive observation ranged from twenty
four hours to thirty five days. We found that more than 55 per cent of the
sources showed significant variability, but often only one or a few spectral
features were varying significantly. Numerous type of variability were found in
our sample: low-variable, periodic, irregular, synchronised and anti-correlated
between features and steadily raising or falling flux. Our analysis techniques
also uncover new variability trends for several sources. The maser monitoring
program is one of the first single-dish science initiatives at the Irbene radio
telescope complex, initiated shortly after the instrument's reconstruction and
upgrades. Our findings unequivocally demonstrate its suitability for maser
research purposes.
