Monday
If there exists a more dependable phenomenon in the observable universe, science has yet to document it. Monday arrives with clockwork precision, emerging from the shadow of Sunday with absolute certainty. Unlike comets, eclipses, or meteor showers, which require complex calculations to predict, Monday's schedule can be determined by any child with basic calendrical literacy.
This reliability extends to its emotional payload. The sense of obligation, the weight of accumulated tasks, the dissolution of weekend freedoms these sensations reproduce themselves with remarkable consistency across cultures, continents, and centuries. Monday has never once failed to arrive on schedule.
Wolf
The wolf, whilst a magnificently consistent predator within its ecological niche, demonstrates significant variability in behaviour. Pack dynamics, seasonal changes, prey availability, and environmental pressures all influence when and whether a wolf will appear. Wolves may go weeks between successful hunts, demonstrating an irregular operational pattern.
Furthermore, wolf populations have proven distressingly unreliable from a conservation perspective. Human expansion has reduced their numbers dramatically, with the species entirely absent from many of its historical territories. One cannot, in good scientific conscience, describe as 'reliable' a creature that may cease to exist in certain regions.