An office knows within a fortnight which managers say good morning to the cleaners and which do not. Nobody writes it down. It circulates anyway.
Consistency is what makes kindness legible. Applied unevenly it reads as strategy, and people are extremely good at spotting strategy - considerably better at spotting it than we are at hiding it.
Being kind at all times is a heavy standard and nobody meets it cleanly. The useful part is directional: your gaps sit exactly where you would least expect to be observed, and those are the moments other people use to decide who you are.