Serious, use everyday:

• ultra-low 2lm output for crawling in aisles, not bothering/disturbing anyone
• ultra-high 2000lm for pointing at things, and for emergency illumination where the brightest, the best (point at ceiling to not blind anyone)
• fade-up or down the mid-range for general work situations where ambiant light isn't sufficient (or you're just getting old, uh)

Some people would argue about the strobe and S.O.S functions out in nature, or even sell the 2000lm as defence against aggression

Very low, low, medium, high, turbo

Enthusiast/custom lights may have more complicated lights that have different patterns, custom programming, presets, etc

The instructions for my Emisar flashlights look like a map to a pirate’s treasure but in space